What about FN .264 LICC?

I liked the 3-lug on the XCR-L I had. I just wasn’t a fan of how front heavy the balance was with the full length handguard. Which ultimate lead to selling to a coworker. A minor annoyance was all the screw points: barrel mount bolt, extractor screws, stock position fastening screw.

Edit: at least FN, like Sig makes an effort to sell many of their designs on the commercial market.

Yeah. 3 lug and beefy.

AR15....very dainty. But then again 556 is a fine little lady. Doesn't need a lot to get her going in and coming out. Little.

11.5 inch Colt Commando (SR15) to me is the Ultimate in balance. Hard to beat 5-6 lbs like that.

So agile yet so much power and capability under 150 meters.

No sharp edges to cut your knuckles or fingers on. Fast handling. Can manhandle it fast..even with a thicker barrel.
 
This was something I didn’t really understand with the MCX - if the intent was multi-caliber with 762x39 on the table why did they go with an AR15 style bolt over something like what you made? They were already making a proprietary barrel extension, gas piston, and BCG. Why keep the AR-15 bolt especially knowing it’s limitations.
This bolt that came out of my SIG is like the Titan bolts I made. It is very close to the KAC E3 which was made for the 5.56, I designed mine a little differently for the .441 case head.
Titan is the middle bolt, Super bolts in 6.8 I machined is 2nd from left, 750XD and 800 series 4th and 5th are for .473 cartridges in a AR15.
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This bolt that came out of my SIG is like the Titan bolts I made. It is very close to the KAC E3 which was made for the 5.56, I designed mine a little differently for the .441 case head.
Titan is the middle bolt, Super bolts in 6.8 I machined is 2nd from left, 750XD and 800 series 4th and 5th are for .473 cartridges in a AR15.
View attachment 8114356
Oh I see a Spear LT!

Any chance you might get back into the game and make 6mm Predator barrels for the Spear LT/MCX?
 
Punch in some numbers and let us know. It's free for anybody to use — unlike your Secret Squirrel "forum."
Yes I've been using it for years but I'm not that interested. I'm just here to kick the hornets nest.
So the 6.5LICC and the 6.8x51 is the same diameter and the 6.5LICC is only .2" shorter, do you really think it's going to make a big difference in weight and size of the rifle and ammo or recoil or is it you just can't stand that they chose a 6.8mm over the 6.5MM?
 
Oh I see a Spear LT!

Any chance you might get back into the game and make 6mm Predator barrels for the Spear LT/MCX?
No, they aren't near popular enough yet but I would love to have one. They would need bolts, extensions and barrels to do a swap, then use the piston assembly off a donor barrel.
 
This bolt that came out of my SIG is like the Titan bolts I made. It is very close to the KAC E3 which was made for the 5.56, I designed mine a little differently for the .441 case head.
Titan is the middle bolt, Super bolts in 6.8 I machined is 2nd from left, 750XD and 800 series 4th and 5th are for .473 cartridges in a AR15.
View attachment 8114356

I love that 5th bolt.

So would Steve Holland.
 
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I love that 5th bolt.

So would Steve Holland.
He knew about them as well as Murray. Murray contacted me about making a few bolts to convert a MG42 to his 7mmUIAC. He was on the right track IMO, I wasn't personally interested in the 7mm but he had a good reason and knew what he was doing. You know how the military works, they take parts of your good idea and spin them into a political nightmare of who pays the largest kickbacks. Personally I think they should have enlarged the AR15platform a little and stayed with a smaller cartridge for the main percentage of troops then used this NGSW for special groups and GPMG.
 
This NGSW program has been going on since long before 2019. Original tests were conducted with the 6.5 Creedmoor, 6.8x51 and 308.
This posted 8/2019 -NGSW
"According to the solicitation, the duration for each prototype OTA is estimated to be up to eight years. The first 27 months will be for prototyping the NGSW-R, NGSW-AR, and ammunition. Following this prototyping effort, there may be additional iterative prototyping efforts for the NGSW-R, NGSW-AR, and ammunition. These iterative prototyping efforts will each have separate durations and will occur within the eight year duration."

I'll post more as I find it and edit here, the thread is almost 200 pages so it may take a while.


It appears Sig did most of the testing and their hybrid ammo steel case head and brass case is how they get the performance, the Sig Cross rifles were the first to be released with that info. Also appears the US military took that info and told everyone else to better it if they could.

https://www.military.com/daily-news/2019/10/27/inside-armys-quest-revolutionary-new-bullet.html

In terms of the Objective velocity, its likely that the Objective for either the carbine or LMG is 3200fps+.

This is based on the the previous rumors of NGSW originating with the "6.8 HVAP" - supposedly around 3400fps - which also explains why they believed it possible to defeat Level IV at 600m. A .285 G7 130gr @ 3400fps would have a 600m impact velocity of 2300fps, comparable to an AK at the muzzle, which could plausibly penetrate Level IV if the projectile is greatly enhanced over current M993.

And 3200fps is supported by the MARS NGSW entry - 140gr @ 3200fps from a 18" barrel:

What will really make or break the AP requirement is projectile design.


We're really left with 2 options.


1. The Army hasn't seen Buffman's testing and is unaware of how tough current Level IV really is vis a vis M993 (130gr M993 stopped @ 2850fps by IV.)


2. The Army has developed a substantially better AP projectile technology then current M993.


In terms of Option 2, several theories.


2a: Rather then traditional Tungsten Carbide (WC), the Army is using Tungsten Heavy Alloy (WHA), which is denser and better penetrating.


2b: The Army is using a better / new WC/WHA sintering method, making the penetrator less prone to shattering/deforming when impacting the Ceramic.


2c: The exposed Tungsten penetrator of the new projectile substantially boosts penetration vs a traditional jacketed penetrator like M993.


2d: The new AP projectile uses a different material then copper for the base. This material, through superior acoustic impedance, allows the base to synergize with the tungsten tip, and perform similarly to a full length tungsten penetrator. Ie a 15mm Tungsten Tip + 20mm Material X penetrates like a 35mm long Tungsten penetrator.


2e: The new AP projectile is not an EPR like M80A1/M855A1, but is a new style of bullet called Aeroshell. This pairs a full length WHA penetrator with a polymer jacket. Whereas M993 is a 130gr projectile with 90gr tunsgten core, this would be a 130gr bullets with a 120gr full length core:
https://www.armytimes.com/resizer/3...aws.com/public/4J6OFQLIABCFZBVWA5FK53ONG4.jpg


If 2 is true - they've made a better AP projectile - then the answer is likely found in some combination of 2a-2d.

Now per Buffman, we've seen Level IV stop M80A1 steel tip at 3400fps from 40' away. Given the AP requirement of NGSW, it strains credulity (even for the Army) that they would be trying to achieve their AP goals with a steel tip projectile.

Meanwhile, previous mention of ADVAP mentions Tungsten:
https://www.thefirearmblog.com/blog...red-epr-based-design-cheaper-quicker-produce/


"What does everyone think about the .264 USA modified to use TV neckless cases? Would that be a better compromise solution than 6.5CM?"

6.5 CM basically is .264 USA, but with less hassle.

.264 USA = 6.5x48mm; 123gr @ 2670fps from 16"; 123gr Brass 20.43g

6.5 CM = 6.5x49mm; 120gr @ 2720fps from 16"; 123gr Brass 22.2g

https://rifleshooter.com/2016/02/6-...el-length-on-velocity-cutting-up-a-creedmoor/

https://www.thefirearmblog.com/blog...ibers-021-us-army-marksmanship-units-264-usa/

A 25rd Pmag 7.62/6.5 = the length of a 30rd 5.56 magazine.

Military is looking at this 6.8x51 like it is lighter than a 308, better ballistics than a 308, better armor defeating ability than a 308. They aren't looking at it like they are making the 5.56 better.
 
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That is the same article I posted a week or 2 ago here somewhere.
https://soldiersystems.net/2023/01/...warfare-technology-support-directorate-iwtsd/


That looks pretty good.

"70% more energy and twice as accurate as M4"

What about a twice as accurate M4 (SR15) in .22 Nosler with 70% less energy then 6.5 LICC using DU rounds or a new Tungsten. Jk..kinda.

I wonder if a ceramic in the front and tungsten in the rear would do okay like a tandem warhead. Crack the Ceramic and smash through like a multi hit. Use the Ceramic plate as frag for you.

Ceramic dust would mess your lungs up.

Tungsten would bounce like a bouncy ball.
So would DU. Maybe Ceramic and Mild Steel.

I need a slow motion simulator with all materials available to play with.
 
Don't know how I missed this at SHOT Show 2023, but somebody posted about FN's new .264 LICC and after looking into it, it seems pretty cool.

The .264 LICC (Lightweight Intermediate Caliber Cartridge) is based on the .264 USA, which is a 6.5x48 cartridge developed by the AMU (Army Marksmanship Unit) with a case head of .441, like the 6.5 Grendel; it’s basically a stretched Grendel. A head diameter of .441, like the 6.5 Grendel, 6mmARC, and .264 USA, is the largest that can reliably double-stack within the dimensions of the AR15 magazine well. If you move up to .473 you can’t double-stack in the AR15; you need a redesigned magazine (especially if using polymer mags) and mag well.

FN's .264 LICC (6.5x43 with a 2.5” COAL) has a case head of .473, like the .308 Winchester family of cartridges, as well as the newer 6mm GT. The 6mm GT has a case length of 44mm (1.73"), and a 24" bbl velocity of 3075 fps with a 110gr bullet at 62,100 psi pressure, according to Hodgdon’s reloading data.

FN has not released specs on the .264 LICC, but a 6.5x43 with a 110gr in a 24" bbl should get 3100 fps (add 25 fps for the increased surface area “piston effect”), and a more optimum weighted 115gr should get 3050 fps. Pressures should be around 62k psi, much better than the 80k psi of the dead-end 6.8 NGSW.

Note: 62k psi is still gonna kick too much for the average troop, so a recoil-reducing mechanism like “constant recoil” is a must.

A 6.5mm 115gr hybrd OTM using existing Berger ogives can have a G1 BC of .610. Using the 25 fps per barrel inch rule of thumb starting with a 24” bbl at 3050 fps, a 20” bbl would get 2950, a 16” gets 2850, and a 12” gets 2750.

Ballistics could be pretty good in a compact package no bigger than an AR15, which the Ruger SFAR has proven possible. Cases are two-part and made of stainless steel and are 20% lighter than comparable brass. More compact cartridges like this help maximize the soldier’s basic load over the 6.8 NGSW. Gets 25 rounds in the same length as a 5.56 30-round mag.

YouTube video HERE.

Is FN on to something, or not?
Didn’t Daniel Horner use that in a 12.5” barrel for AMU? Called it the 6.5 gremlin?
 
My comments are based on the premise that 5.56x45 isn’t going anywhere anytime soon due to how many people carry it, and will continue to carry 5.56 weapons even in the Line Infantry. The main cartridge that needs to be replaced and should never have been born is 7.62x51 NATO. A lot of civilians and even most military personnel are fixated on the idea that 5.56 is being replaced, without thinking through the logistics and weapon weight across the force.

.257”/6.35mm and 6.5mm out-perform .277”/6.8mm for sectional density and retained velocity for armor-defeat at range. That 131-135gr .257” can be fired at lower mv, and impact the target at higher velocity than the 135gr NGSW .277” projectile, with significantly-better Sectional Density, fired from a smaller weapon that has less recoil, a smaller overall cartridge profile from smaller magazines, and therefore more ammunition carrying capacity. The Army managed to seize defeat from the jaws of victory once again with the .277” diameter requirement, even after 140 years of metallic cartridge technology lessons-learned across countless expeditionary campaigns and world wars.

If anyone claims that the .277” 130-135gr has an advantage in SD for armor defeat, it means they don’t understand much about external or terminal ballistics, or leans towards the probability that they were focused on muzzle velocity and maybe barrel life with a high pressure cartridge using their typical brute force mentality. Less overbore would allow longer barrel life for machineguns especially, but with back-end weight penalties that scale into the receiver and reciprocating mass.

The problem with 6.8 and 7mm is cartridge weight, form factor, and the necessary magazine or linked cartridge bulk to support it, which is a non-starter for general issue. They would have been great in the 1930s-1950s for LMGs and DMR/Sniper Systems, but the US was still hell-bent on the inefficient .30 bore for some reason, even after being shown-up with 7x57 Mauser, or our own positive experiences with 6mm Lee Navy.

Even the .264 LICC with .473” case head diameter is a non-starter because you end up with magazines that are the same width as SR-25 mags, and require about the same pouch volume/distribution on the soldier’s load. This limits ammunition carrying capacity, although it would be a small step in the right direction away from 7.62x51.

My perspective for the last 15 years has been that a .441” case head should replace 7.62 NATO, with comparable downrange performance, but 50% of the recoil. That would free up a lot of maneuverability and endurance for dismounted soldiers who currently carry M240s and its ammunition, as well as SR-25s/M110s, while increasing the hit probability substantially.

The 600m armor defeat goal is flawed for a general issue carbine due to all the penalties it imposes 100% of the time, with no practical application outside of Snipers, DMs, and Machinegunners.

Also notice that NGSW original threshold has been walked back repeatedly from 3400fps, to 3200fps, then 3000fps. The NGSW carbine still has impressive performance from a 13” barrel spitting that 135gr at 2900fps, but that will not equate to a 600m armor defeat based on the original target threshold. It does provide increased armor defeat range, but they are tight-lipped about what that actually is for obvious reasons.

The other problem is that once something like this gets nailed-down, the threat can just improve their armor resistance, or counter it with smaller, lighter cartridges that allow fire superiority like the AK and RPD had over the M14/M60, which was identified at Fort Benning in classified force-on-force exercises in the early 1960s.
 
Ammo bulk, both on a logistical mass scale and for an individual troop's basic load are a valid concern, but the difference in the thickness of a double-stack of .441 vs .473 case heads is about 1.5mm. Difference seems minimal.
 
Just read through this entire thread. Really angers me to know that there is a potential solution out there to defeat Level IV using existing military/NATO spec calibers. I was part of the R&D team that developed this technology for Gila Defense Systems. Back in 2018 was the first and only time I discussed this in public. I believe my input (same handle as here) starts on this page:


Unfortunately the military just renewed the secrecy order for the third time, so can't elaborate on the technology. What does that tell you? Just so happens 2018 was the last time I was on this site. They have there own little click over there that rules the roost and based on how I was treated, never went back.
 
Ammo bulk, both on a logistical mass scale and for an individual troop's basic load are a valid concern, but the difference in the thickness of a double-stack of .441 vs .473 case heads is about 1.5mm. Difference seems minimal.
When you carry the magazines in belt, vest, or plate carrier-mounted pouches, the difference becomes quite noticeable mainly because of the projectile weights stacked with each other pulling away from your center of gravity. Same for linked.

The difference between carrying 6x 30rd 5.56 mags vs 4x 7.62x51 20rd mags is night and day in favor of the 5.56 NATO. Same with those Six8 magazines, but not as bad as 7.62. From the side, they look like they’re only a bit taller, but their thickness is more like an SR-25 PMAG and they take up more room as a result. I could carry anywhere from a 7x 30rd mag basic load, to a 14x mag load quite comfortably close to sea level.

With the SAW, I could carry 4x 200rd drums and 3-4x 100rd nutsacks on my fighting load, depending on the conditions/terrain. You can distribute 200rd drums throughout the Rifle Squad as well into guys’ assault packs. The new 6.8x51 NGSW reduces the LMG gunner basic load considerably for the same weight, so they’ll have to practice better fire discipline.

You see the same thing with 7.62x39 magazines. Those curved AK mags freaking suck to carry, especially for little guys.

For DMs and Snipers, the 6.5 LICC is a step in the right direction but still a bit too close to 7.62 NATO profile for my liking. Should be nice in a belt-fed LMG though since the COL is shorter, but round count won’t be the same as the SAW.

I wouldn’t mind a slightly-longer COL at 2.500”, but with a .441” case head, lighter case material for the DM/Sniper and LMG. As long as we get rid of 7.62x51 and go to a lighter/smaller cartridge with way less recoil and better downrange performance, it will be the right move.
 
FN's 264LICC was at AUSA over the weekend and there's some news HERE, but it's not much.

The weapon seems to make some common sense ergonomic improvements for ambidextrous use, but I'm mostly interested in reports on the performance of the 264 LICC cartridge.
 
My comments are based on the premise that 5.56x45 isn’t going anywhere anytime soon due to how many people carry it, and will continue to carry 5.56 weapons even in the Line Infantry. The main cartridge that needs to be replaced and should never have been born is 7.62x51 NATO. A lot of civilians and even most military personnel are fixated on the idea that 5.56 is being replaced, without thinking through the logistics and weapon weight across the force.

I think 5.56x45 has a loooong life ahead of it being what it always should have been: an excellent PDW/Short Carbine cartridge. The loadings that are specifically designed for SBR use have some great performance, and my guess is we'll see either the M4A1 or some variation without the buffer system (MCX spear-lt maybe?) become dominant as a standard issue armament for anyone not "front line"

.257”/6.35mm and 6.5mm out-perform .277”/6.8mm for sectional density and retained velocity for armor-defeat at range. That 131-135gr .257” can be fired at lower mv, and impact the target at higher velocity than the 135gr NGSW .277” projectile, with significantly-better Sectional Density, fired from a smaller weapon that has less recoil, a smaller overall cartridge profile from smaller magazines, and therefore more ammunition carrying capacity. The Army managed to seize defeat from the jaws of victory once again with the .277” diameter requirement, even after 140 years of metallic cartridge technology lessons-learned across countless expeditionary campaigns and world wars.

If anyone claims that the .277” 130-135gr has an advantage in SD for armor defeat, it means they don’t understand much about external or terminal ballistics, or leans towards the probability that they were focused on muzzle velocity and maybe barrel life with a high pressure cartridge using their typical brute force mentality. Less overbore would allow longer barrel life for machineguns especially, but with back-end weight penalties that scale into the receiver and reciprocating mass.
I think the reason for the 6.8mm diameter given was not to do with its ballistic properties, but rather material properties and how they interact on impact. I did a little modeling of a supposed "M80A1 Alike" based on what we publically know about the 855A1, 80A1 and the test/prototype 6.5CM ""A1"" projectile design.

in the impact models the 6.8 when modeled at the same general proportions seemed to have a greater chance of generating the "happy accident we swear" controlled fracturing effect.

At least that is my best educated guess as to why that diameter was chosen over potential alternatives.

Its telling that the biggest adjuncts to the NGSW are refits of the heavier GPMGs to the 6.8x51 cartridge
 
If you stack the same mass into a longer projectile, the cascading "train car" effect for armor defeat favors the better SD/longer projectile, from all I’ve seen in the barrier and armor defeat high-speed video and DoD studies. In this case, not only will a 6.35mm or 6.5mm projectile of the exact same mass impact the target with higher speed/more momentum than a 6.8mm projectile, but will have that longer tail-end core mass to ripple-effect with sequential impacts that pound through the barrier. What model are you using and does it not reflect this?

I’m perfectly willing to submit to better data that I’m not privy to that may have steered the Army in the direction of .277”, but to be honest, the best and brightest minds in the Army are primarily allocated to Aviation first, then to Artillery/Long Range Fires/Air Defense, Medical, Intel, Chemical, Electronic Warfare, Cyber Warfare, Psyops, Civil Affairs, Special Forces, and JAG. As gun guys, we get fixated on a tiny fraction of the overall force structure and personnel allocations, expecting the best technology to be gifted to us across the board, when in reality, the senior leadership not only doesn’t care much about the Infantry, but can’t afford to care as much about it as we might.

Even in the rare event that we get a PEO over a program with near-genius level intellect and subject matter familiarization, they’re only in that job over a particular program for maybe 2-3 years, then they move on to some other inane ticket-punch mandated by their Branch managers. Most programs require the PEO and other seniors in that program to spend a lot of time getting educated on the subject, though some can surprise you. There are some geeks who survive a few enlistments into senior ranks miraculously, and contribute greatly to the technical aspects of a program, but they get reassigned often, right as traction is headed towards a peak mile mark, then the program deflates and the cycle repeats itself.

If I was in leadership’s shoes and faced with having the smarter people running AH-64E Digital Apache net-centric integration or Patriot PAC-3 Missile Segment Enhancement upgrades, versus a new rifle for the Infantry, it’s an easy decision that doesn’t even have to be made or explained. A single eff-up with an Apache gunning down friendlies (2nd most likely offender in fratricide incidents behind the A-10) or a Patriot failing to intercept a Theater Ballistic Missile is much more consequential than "Joe and his pea-shooter".

This is my take on why progress is so slow for Infantry weapons and cartridges. I even think 6.8x51 would have been the wrong direction to go in the 1930s, but better than doubling-down on .30 cal 1906.

No matter what they decide, there are going to be at least 2 cartridges in the Infantry at the Platoon level, as there should be.
 
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There is a lot of video with Steve Holland explaining the development of the 6.8 SPC. Dr. Gary Roberts was involved as well and per Steve, THAT'S why the .27 caliber was chosen. They wanted a cartridge that did as much or more damage as the 7.62x39. I think every bullet combination was actually tested using the parent case, .224, .257, .264, .284. Their results pointed to .277.

I would think if there was testing of various calibers someone here would know about it and how 6.8x51 was chosen. It would not surprise me if they just ran with it because of that past testing.
 
There is a lot of video with Steve Holland explaining the development of the 6.8 SPC. Dr. Gary Roberts was involved as well and per Steve, THAT'S why the .27 caliber was chosen. They wanted a cartridge that did as much or more damage as the 7.62x39. I think every bullet combination was actually tested using the parent case, .224, .257, .264, .284. Their results pointed to .277.

I would think if there was testing of various calibers someone here would know about it and how 6.8x51 was chosen. It would not surprise me if they just ran with it because of that past testing.
Steve Holland is a very interesting character. He was a Green Light Team 18E from back in the 1980s. He bypassed the normal commo section work that 18Es would do after SFQC at Group, before getting assigned to their ODAs, because they needed a commo guy on one of the Teams in the Green Light Company, which was a priority mission set in the Cold War. Green Light = HALO qualified ODAs that jumped-in the MK-54 SADM (nuke).

Anyway, he ended up in a senior NCO products development lead position in 5th Group, where he went around asking the end-users what it was that they wanted. At the time, there were no less than 3 different programs for small arms development specific to AR-15 carbines and rifles for SOF, pre-9/11.

1. The Special Purpose Receiver/Rifle. The SPR was focused on a Light Sniper System based on modifications to 723s and 727s within JSOC. Army JSOC Sniper Troops (former RRD, Ranger, SF, and LRS guys who had been to USMC SS Course, SOTIC, and/or Benning and Unit-internal Sniper Troop training) had the armorers build their 723 uppers into highly-accurate lightweight precision carbines with free-float tubes and optics, as well as the AIM-1 or PAQ-4C LAM, suppressed with Ops Inc cans, for close target Recce and precision fires support when over-watching for Assaulters. Imagine a Colt 723 with a 12.7” SR-25 fiberglass or Bushmaster V-Match aluminum free-float tube, a FSB pocket cut, rail sections attached for the LAM, Surefire, VFG, and provisions for bipod-mounting dependent on the mission profile, with an Ops Inc can sleeved under the handguard. I have yet to see any online photos of these, but the ones I’ve personally seen were well before the SPR program. The later ones had shaved uppers with Weaver/early 1913-type rails installed on them before/as the M4 upper went into production.

iu


Dam Neck guys saw these Sniper Support carbines being used in The Unit by their Army counterparts during JFXs, and wanted their armorers to make the same thing for them. By the time Dam Neck started doing it, the M4 had just gone into production, so there are some photos of Dam Neck Assaulters with little free-float 727 carbines, and some with the longer barreled Sniper Support/Recce carbines like this:

iu


SF SOTIC Committee guys at Range 37 saw these JSOC Sniper Carbines, and thought they would be good for SF and USASOC as well. The joint requests from Army SF and white-side NAVSPECWAR in the regular Teams led to Crane Indiana doing what we all came to know as the SPR, but its origins were really in The Unit/Army JSOC in the early 1990s.

Mk12_Mod0_Profile.jpg


2. The Enhanced Rifle Cartridge Program. There were other requests for an improved barrier defeat and CQB performance cartridge to fit inside the M16A2 Carbine (723 and 727) coming from the CQB Committees in both the Army and Navy, as well as unnamed entities with the ability to fund a program with Colt that dates back into the late 1980s. That resulted in Colt’s work on the Colt AR-15 in 7.62x39, which was later marketed to the civilian sector as the 7.62x39 Sporter. One of the ideas was to be able to use host nation supplies of common 7.62x39 ammunition but in the more familiar, compact Colt Carbine format used by some units in SF.

iu


ECR divided into 3 camps. A) 7.62x39 UW Carbine, B) Improved terminal performance 5.56x45, and C) An entirely new Special Purpose Cartridge. Steve Holland at 5th Group Special Products Development and Chris Murray from the AMU began working on a new cartridge that would provide more momentum and terminal ballistics effects within 0-300m from carbines, since 7.62x39 suffered from magazine configuration issues in the AR-15 at the time. After testing with calibers ranging from 6mm to 30 cal in a shortened 30 Remington parent case, they settled on .277”/6.8mm as the bullet diameter to nail down and proceed with that could still fit inside the standard profile of a 30rd M16 STANG magazine and soldiers’ mag pouches. This became known as the 6.8x43 or 6.8 SPC. It was originally supposed to fit and function in existing magazines, but of course did not.

SPC_trials1_zps09scamsg.jpg


3. DMR rifle cartridge. As the momentum began to build within USASOC and SOCOM for their new Special Purpose Receiver/Rifle in the DMR role to augment the precision fires within small units where they used to use M21s, M14s, and the new SR-25s, they also needed a new accurate cartridge with better downrange retention of momentum. Within JSOC, they had been using 68gr and 69gr Match ammo loaded for them independent from the normal DoD acquisition channels in the early 1990s, along with a heavy diet of M855. The 75gr Hornady, 77gr Nosler and 77gr SMK (non cannelure) were seen as the most promising, highest BC projectile they could magazine-COL load, so in conjunction with the AMU and the private sector, the Mk.262 cartridge was born. Original 77gr SMK didn’t have a cannelure, while the 77gr Nosler did. USMC became very interested in the SPR program as well by the early 2000s, and spent significant resources funding their own testing before ordering over 1 millions rounds of it.

The 6.8x43 proponents tried to get it to also do the SPR/DMR role with the Murray DMR chamber, but the supersonic reach and wind drift was worse than 5.56, and 77gr SMK extended the supersonic reach farther, with less drop as a result. SOCOM and USMC also funded several different 5.56x45 cartridges that improved the terminal performance, and by the time the 6.8 ammunition went into production, the ECR and DMR requirements were already satisfied in 5.56x45 without having to make a caliber or magazine change within the operational units.

That’s how we got:

Mk.262 Mod 0
Mk.262 Mod 1
5.56 Optimized/Brown Tip Barnes TSX
Mk.318 Mod 0 SOST

And eventually
M855A1

I haven’t seen someone make a connection between 6.8x43 and 6.8x51 for projectile diameter demand baseline, but wouldn’t be surprised if it was influenced that way. The interesting thing is all the recently-retired US Army SOTIC and Navy SEAL Sniper guys have the same reaction to the NGSW, which is that it seems like a DMR, not something you would issue out to everyone due to weight, bulk, limited mag capacity and ammo carriage on soldier’s load.
 
I haven’t seen someone make a connection between 6.8x43 and 6.8x51 for projectile diameter demand baseline, but wouldn’t be surprised if it was influenced that way. The interesting thing is all the recently-retired US Army SOTIC and Navy SEAL Sniper guys have the same reaction to the NGSW, which is that it seems like a DMR, not something you would issue out to everyone due to weight, bulk, limited mag capacity and ammo carriage on soldier’s load.

This article is quoting the tests in the past while speaking of the NGSW. Even an idiot general gives his two cents. This appears to be .30/06 all over again with "we have all this brass, let's just neck it down."

 
Steve Holland is a very interesting character. He was a Green Light Team 18E from back in the 1980s. He bypassed the normal commo section work that 18Es would do after SFQC at Group, before getting assigned to their ODAs, because they needed a commo guy on one of the Teams in the Green Light Company, which was a priority mission set in the Cold War. Green Light = HALO qualified ODAs that jumped-in the MK-54 SADM (nuke).

Anyway, he ended up in a senior NCO products development lead position in 5th Group, where he went around asking the end-users what it was that they wanted. At the time, there were no less than 3 different programs for small arms development specific to AR-15 carbines and rifles for SOF, pre-9/11.

1. The Special Purpose Receiver/Rifle. The SPR was focused on a Light Sniper System based on modifications to 723s and 727s within JSOC. Army JSOC Sniper Troops (former RRD, Ranger, SF, and LRS guys who had been to USMC SS Course, SOTIC, and/or Benning and Unit-internal Sniper Troop training) had the armorers build their 723 uppers into highly-accurate lightweight precision carbines with free-float tubes and optics, as well as the AIM-1 or PAQ-4C LAM, suppressed with Ops Inc cans, for close target Recce and precision fires support when over-watching for Assaulters. Imagine a Colt 723 with a 12.7” SR-25 fiberglass or Bushmaster V-Match aluminum free-float tube, a FSB pocket cut, rail sections attached for the LAM, Surefire, VFG, and provisions for bipod-mounting dependent on the mission profile, with an Ops Inc can sleeved under the handguard. I have yet to see any online photos of these, but the ones I’ve personally seen were well before the SPR program. The later ones had shaved uppers with Weaver/early 1913-type rails installed on them before/as the M4 upper went into production.

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Dam Neck guys saw these Sniper Support carbines being used in The Unit by their Army counterparts during JFXs, and wanted their armorers to make the same thing for them. By the time Dam Neck started doing it, the M4 had just gone into production, so there are some photos of Dam Neck Assaulters with little free-float 727 carbines, and some with the longer barreled Sniper Support/Recce carbines like this:

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SF SOTIC Committee guys at Range 37 saw these JSOC Sniper Carbines, and thought they would be good for SF and USASOC as well. The joint requests from Army SF and white-side NAVSPECWAR in the regular Teams led to Crane Indiana doing what we all came to know as the SPR, but its origins were really in The Unit/Army JSOC in the early 1990s.

Mk12_Mod0_Profile.jpg


2. The Enhanced Rifle Cartridge Program. There were other requests for an improved barrier defeat and CQB performance cartridge to fit inside the M16A2 Carbine (723 and 727) coming from the CQB Committees in both the Army and Navy, as well as unnamed entities with the ability to fund a program with Colt that dates back into the late 1980s. That resulted in Colt’s work on the Colt AR-15 in 7.62x39, which was later marketed to the civilian sector as the 7.62x39 Sporter. One of the ideas was to be able to use host nation supplies of common 7.62x39 ammunition but in the more familiar, compact Colt Carbine format used by some units in SF.

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ECR divided into 3 camps. A) 7.62x39 UW Carbine, B) Improved terminal performance 5.56x45, and C) An entirely new Special Purpose Cartridge. Steve Holland at 5th Group Special Products Development and Chris Murray from the AMU began working on a new cartridge that would provide more momentum and terminal ballistics effects within 0-300m from carbines, since 7.62x39 suffered from magazine configuration issues in the AR-15 at the time. After testing with calibers ranging from 6mm to 30 cal in a shortened 30 Remington parent case, they settled on .277”/6.8mm as the bullet diameter to nail down and proceed with that could still fit inside the standard profile of a 30rd M16 STANG magazine and soldiers’ mag pouches. This became known as the 6.8x43 or 6.8 SPC. It was originally supposed to fit and function in existing magazines, but of course did not.

SPC_trials1_zps09scamsg.jpg


3. DMR rifle cartridge. As the momentum began to build within USASOC and SOCOM for their new Special Purpose Receiver/Rifle in the DMR role to augment the precision fires within small units where they used to use M21s, M14s, and the new SR-25s, they also needed a new accurate cartridge with better downrange retention of momentum. Within JSOC, they had been using 68gr and 69gr Match ammo loaded for them independent from the normal DoD acquisition channels in the early 1990s, along with a heavy diet of M855. The 75gr Hornady, 77gr Nosler and 77gr SMK (non cannelure) were seen as the most promising, highest BC projectile they could magazine-COL load, so in conjunction with the AMU and the private sector, the Mk.262 cartridge was born. Original 77gr SMK didn’t have a cannelure, while the 77gr Nosler did. USMC became very interested in the SPR program as well by the early 2000s, and spent significant resources funding their own testing before ordering over 1 millions rounds of it.

The 6.8x43 proponents tried to get it to also do the SPR/DMR role with the Murray DMR chamber, but the supersonic reach and wind drift was worse than 5.56, and 77gr SMK extended the supersonic reach farther, with less drop as a result. SOCOM and USMC also funded several different 5.56x45 cartridges that improved the terminal performance, and by the time the 6.8 ammunition went into production, the ECR and DMR requirements were already satisfied in 5.56x45 without having to make a caliber or magazine change within the operational units.

That’s how we got:

Mk.262 Mod 0
Mk.262 Mod 1
5.56 Optimized/Brown Tip Barnes TSX
Mk.318 Mod 0 SOST

And eventually
M855A1

I haven’t seen someone make a connection between 6.8x43 and 6.8x51 for projectile diameter demand baseline, but wouldn’t be surprised if it was influenced that way. The interesting thing is all the recently-retired US Army SOTIC and Navy SEAL Sniper guys have the same reaction to the NGSW, which is that it seems like a DMR, not something you would issue out to everyone due to weight, bulk, limited mag capacity and ammo carriage on soldier’s load.
I feel like I should be subscribed to your Patreon or Onlyfans and paying you for these posts; such interesting reads.
 
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If you stack the same mass into a longer projectile, the cascading "train car" effect for armor defeat favors the better SD/longer projectile, from all I’ve seen in the barrier and armor defeat high-speed video and DoD studies. In this case, not only will a 6.35mm or 6.5mm projectile of the exact same mass impact the target with higher speed/more momentum than a 6.8mm projectile, but will have that longer tail-end core mass to ripple-effect with sequential impacts that pound through the barrier. What model are you using and does it not reflect this?
Oh I absolutely agree for hard targets, my modeling was actually against non-compressible liquid targets (aka things filled with lots of water, like two and four-legged critters), and the copper being forced outwards by the shape of the steel penetrator, created larger 'petal fragments' more reliably.
 
With that steel cased ammo and higher pressures, they should be able to get close to 18-20” 6.5CM velocities from an 11.5” barrel, but barrel life will of course suffer.

I would rather have something like this than the XM7 for sure, though I am not a fan of .473” cartridge base diameter for general issue.
 
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With that steel cased ammo and higher pressures, they should be able to get close to 18-20” 6.5CM velocities from an 11.5” barrel, but barrel life will of course suffer.

I would rather have something like this than the XM7 for sure, though I am not a fan of .473” cartridge base diameter for general issue.

If they could meet 130gr 6.5CM velocities in the same barrel length with 115gr, that would be phenomenal. This sort of intermediate cartridge is exactly WHERE I would like to live for a semi-auto precision gun....not trying to cram 6ARC into a small-frame and not cutting a beefy large-frame to a shorter barrel.

I've been interested in the 264 USA ever since I heard it existed.
 
.441” case head is about as big as I want to go for a general issue cartridge or even a DM cartridge though.

If anyone is worried about the AR-15 action, just adopt a Fosbery bolt design like KAC did with the SR-15E3 bolt/extension, and great metallurgy with 9310 AISI VAR.

AR-15 action size and ergos are where it’s at, with some tweaks. It will never be out-done in terms of lightweight, accuracy, and reliability until someone finds a way to cut the parts count down even more from the Stoner design.
 
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.441” case head is about as big as I want to go for a general issue cartridge or even a DM cartridge though.

If anyone is worried about the AR-15 action, just adopt a Fosbery bolt design like KAC did with the SR-15E3 bolt/extension, and great metallurgy with 9310 AISI VAR.

AR-15 action size and ergos are where it’s at, with some tweaks. It will never be out-done in terms of lightweight, accuracy, and reliability until someone finds a way to cut the parts count down even more from the Stoner design.

60k PSi 6mm ARC with an E3 bolt/extension seems like the way.
 
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60k PSi 6mm ARC with an E3 bolt/extension seems like the way.
You get faster velocities without chasing pressure with 6.5 Grendel, and you can have a general issue load that is over 3000fps from short barrels with an EPR projectile. Barrel life seems to be better than .308 so far.

One thing people with Grendels never really talk about is barrel life, next replacement barrel sources, or things of that nature that are common with 6.5CM, any of the 6mms, and other over-bore cartridges running higher pressures.
 
You get faster velocities without chasing pressure with 6.5 Grendel, and you can have a general issue load that is over 3000fps from short barrels with an EPR projectile. Barrel life seems to be better than .308 so far.

One thing people with Grendels never really talk about is barrel life, next replacement barrel sources, or things of that nature that are common with 6.5CM, any of the 6mms, and other over-bore cartridges running higher pressures.

We know you LOVE the Grendel and given your positive experience I get why.

However, accept that there are those that don’t want it or have been soured on it despite what “could be”.
 
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We know you LOVE the Grendel and given your positive experience I get why.

However, accept that there are those that don’t want it or have been soured on it despite what “could be”.
When they did the scenario-based testing for the guys who were asking for better LR performance from inside AR-15 sized carbines to supplant their SR-25s, they used 6.5 Grendels from 12” to 18”.

Each of the shooters was asked if there was any scenario where they would have preferred an SR-25 instead, and they unanimously said no.

Hornady then said they could tweak it a little to make it better and did 6mm ARC, only 6mm ARC doesn’t really do anything better. 100-107gr in 6.5 Grendel have faster mv and when you run 103-108gr 6mm next to it, so the Grendel out-performs 6mm at least out to 400-500yds, then they line up out to 1k. Trajectory is still flatter and wind drift is the same.

I didn’t think this was true until I compared real-world 100gr ELD-VT to 103-108gr 6mm Doppler Data from Hornady.

Grendel does it with less chamber pressure as well, no need to really chase it.

I only care about performance and how the trade-offs are managed. I want lightweight, compact, higher performance downrange, ease of self-spotting, and high mag capacity in reasonable volume for the soldier’s load.
 
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When they did the scenario-based testing for the guys who were asking for better LR performance from inside AR-15 sized carbines to supplant their SR-25s, they used 6.5 Grendels from 12” to 18”.

Each of the shooters was asked if there was any scenario where they would have preferred an SR-25 instead, and they unanimously said no.

Who exactly?
It doesn't exactly blow my mind that someone doesn't want to mess with an SR25...especially chambered in 308

Hornady then said they could tweak it a little to make it better and did 6mm ARC, only 6mm ARC doesn’t really do anything better. 100-107gr in 6.5 Grendel have faster mv and when you run 103-108gr 6mm next to it, so the Grendel out-performs 6mm at least out to 400-500yds, then they line up out to 1k. Trajectory is still flatter and wind drift is the same.

I didn’t think this was true until I compared real-world 100gr ELD-VT to 103-108gr 6mm Doppler Data from Hornady.

Grendel does it with less chamber pressure as well, no need to really chase it.

If you say so....

Does this also hold true with apples to apples factory ammo?....like Hornady.

If somebody had a 6.5grendel like Geissele has the 6 ARC I might care. It took the 6 ARC for things in this family to start moving again.
Not to say 6 ARC isn't without its complications as well (largely mags that don't suck).


I only care about performance and how the trade-offs are managed. I want lightweight, compact, higher performance downrange, ease of self-spotting, and high mag capacity in reasonable volume for the soldier’s load.

I feel ya. The 220 Rus family/.441" cartridges just don't do it for me. In any Semi auto, I'm leary as hell of deviating from 5.56/.378" base, but would be willing to go as far as the 6.8/.422" base cartridges even if it meant using some specialty LWRC sized receiver set, but the ARC/Grendel family have exhibited far too much in terms of reliability for me to pursue either with my own money.
 
The problems with SR-25s and any 7.62 NATO carbine/rifle is running in and out of the house, soldier’s load/limited basic load/higher weight/volume, muzzle blast, recoil/self-spot, reliability. The downrange performance/effective range justified its limited distribution among shooters in Sniper/Recce Troop sections, with the penalties as a price you had to pay to have the reach. This has been enough of a problem to dissuade most shooters from taking an SR-25. So in a Recce Troop section of 8 guys, you might have 1 who actually took an SR-25, while several others would use free-floated ARs meant to fill the same role, but limited to 5.56:


Bottom row: M4A1 w/RDS, FF Recce Carbine with Japanese 1.5-4.5 LPVO, FF Recce Carbine with RDS, 20” SR-25 Light Match Rifle w/M3A and KAC suppressor stowed away in his kit
a1cac8d7-f17a-4d21-8c59-21e348f804a0.heic


6.8x51 brings all of those same problems that 7.62x51 does, makes some of them worse, and introduces new ones with throat/barrel/gas port early wear, while being introduced in a less-accurate platform with an external piston and barrel mating design that is currently producing 2-4 MOA groups as the norm.

The .264 USA/.264 LICC bridges the gap between 7.62 NATO/6.8x51 NGSW and the shorter cartridges, so I like it a lot better, but still would prefer a smaller case head. You can achieve the Objective and Threshold requirements they’re specifying without even pushing the pressures if you use an efficient case and propellant.

With the new wave of high performance intermediate cartridges hitting the AR-15 frame since 2003, we’ve shown that you can have the same or better supersonic reach as 7.62 NATO without the other penalties, and ease of self-spotting.

For the 100gr ELD-VT, I have only shot it in factory ammo form. It’s doing 2690fps avg from 18” Grendels and not loaded hot at all. Very flat and true with repeatability and tight waterline at 1000yds.

6mm ARC 16-18” velocities

You’re looking at 2408-2590fps from Hide members’ real world data with 103gr-108gr out of 16-18” ARs.

6mm AR has been around almost as long as 6.5 Grendel. Hi-Power guys were shooting 6mm PPC with Colt 7.62x39 bolts already back in the 1990s, which is what Arne Brennan necked-up to 6.5mm for the 6.5 PPC. Bill A. and Janne Pohjoispää moved the shoulder forward for more case capacity and fine-tuned the case wall and neck geometry for the 6.5 Grendel.

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As soon as Grendel brass started flowing to the US in late 2003, the Hi-Power guys necked it down to 6mm and Rob Whitley made the 6mm AR. I’ve shot 6mm AR since no later than 2012 in friends’ guns who got into it for predator hunting and hi-power.

Shooting 100gr ELD-VT or 107gr SMKs in Grendel is indistinguishable from shooter perspective with 105gr 6mm AR. Once you shoot 123gr in Grendel, then you clearly see your difference in drop and Time of Flight.

A problem that always contained 6mm AR was velocity, so that’s why Whitley made the 6mm AR Turbo and AR Turbo 40, both of which blow the shoulder even further for more case capacity. To get the velocities they were going for, he went to 26-28” barrels and was still pushing the loads, basically trying to chase 6 BR and Dasher.

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For pressure containment parts durability, I still haven’t had a failure and I’ve been shooting 6.5 Grendel regularly since 2009, mostly in multi-day courses where we shoot from morning through evening.

The only critical components failures I have had in the AR-15 are in 5.56, where I have cracked bolts at the cam pin hole. That was running abusive CQM schedules and after over 10,000 rounds. Replaced the bolt and action spring and kept shooting. For any cartridge in any AR, you need proper bolt, extension, and extractor metallurgy.

KAC is making 6mm ARC now with their E3 bolts and extensions, which is another solution set, combined with intelligent metallurgy.

The Army demanded HPT/MPI for the M110, and M110s started breaking bolts, whereas you just don’t hear about such a thing with SR-25s. It’s the same dimensions, same part, only one is done right, and the other is done how the Army insisted it be done.

The problem for 264 LICC is “not invented here” syndrome and the momentum surrounding the 6.8x51 abortion.
 
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If you are starting with a blank'ish slate for the rifle and magazine there is no reason to compromise with the Grendel case. Grendel's case diameter is great, it's case capacity isn't. Add four or five grains capacity to a bolt that will allow 62kPSI of pressure. I like Grendel but when you take it out of the AR15 it makes zero sense.
 
only 6mm ARC doesn’t really do anything better. 100-107gr in 6.5 Grendel have faster mv and when you run 103-108gr 6mm next to it, so the Grendel out-performs 6mm at least out to 400-500yds, then they line up out to 1k. Trajectory is still flatter and wind drift is the same.
You can repeat this as many times as you want, that won't make it true. Plugging the 108 ELD-M at 2600 (Hornady cut-down data) and the 100 ELD-VT at 2650 (2630 in my 18" but I'll spot you an extra 20fps) into 4dof using default environmentals and a 5mph crosswind shows the ARC outperforming in both drop and drift at all ranges 200-1200.
 
You can repeat this as many times as you want, that won't make it true. Plugging the 108 ELD-M at 2600 (Hornady cut-down data) and the 100 ELD-VT at 2650 (2630 in my 18" but I'll spot you an extra 20fps) into 4dof using default environmentals and a 5mph crosswind shows the ARC outperforming in both drop and drift at all ranges 200-1200.

The major difference is his 100ELD-VT going 2650 is within max pressure and your 108ELD-M going 2600 is over pressure almost 10K PSI. What's really wild is users don't understand that a 6mm projectile with more weight than a 6.5mm projectile makes significantly more pressure to reach the same velocity.
 
The major difference is his 100ELD-VT going 2650 is within max pressure and your 108ELD-M going 2600 is over pressure almost 10K PSI. What's really wild is users don't understand that a 6mm projectile with more weight than a 6.5mm projectile makes significantly more pressure to reach the same velocity.
Huh? That's factory Hornady, all of which is loaded at 52ksi.
1730412063135.png

What's really wild is people vastly overestimating the 'piston effect'.
 
Huh? That's factory Hornady, all of which is loaded at 52ksi.
Bullshit. Every single bit of load data available shows that over pressure. You would need a 24" barrel to make that velocity safely. That combination out of an 18" barrel should be making around 2475 at the very best. 2600fps out of an 18" is roughly 60kPSI.
 
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Bullshit. Every single bit of load data available shows that over pressure. You would need a 24" barrel to make that velocity safely. That combination out of an 18" barrel should be making around 2475 at the very best. 2600fps out of an 18" is roughly 60kPSI.
Do you have no concept of burn speed and pressure curve shape? I pulled 2600 as a rough number off the chart above, but the Hornady manual lists two loads that have a 108 going 2575 out of an 18" at max.
 
You can repeat this as many times as you want, that won't make it true. Plugging the 108 ELD-M at 2600 (Hornady cut-down data) and the 100 ELD-VT at 2650 (2630 in my 18" but I'll spot you an extra 20fps) into 4dof using default environmentals and a 5mph crosswind shows the ARC outperforming in both drop and drift at all ranges 200-1200.
I would have agreed with you prior to seeing my 1k results and 4DOF comparison. The 100gr ELD-VT isn’t in the 4DOF program, so I used actual 1000yd results with factory ammo from my 17.6” Grendel. You might have mistakenly used the 100gr ELD-M, which is not the same bullet at all. 100gr ELD-VT looks like a 123gr ELD-M, but with less lead inside. Way longer boat tail, ogive, and OAL than the 100gr ELD-M.

Real world data for 18” 6mm ARCs and Hornady’s load data show it maxed at 2550fps from 18” barrel for 103-105gr, and somehow increases with 108gr and 110gr A-TIP to 2575fps. But you see the factory ammo velocity thread here with 16” bolt guns and 18” gas guns, where it was 2408-2590fps across several different AR-15s.

Real world for 18” Grendels with 100gr ELD-VT factory ammo is 2650-2690fps. The BC might be better as well. Something is happening to where they track almost identically once you get out to mid-range. I posted about it before asking people to sanity-check what I was seeing, and nobody responded with any details contrary to that. I’m open to whatever the data shows. I was planning on getting a 6mm AR for a long time, but after everything I’m seeing with the 100-110gr class in 6.5mm, I’m just not seeing any advantages.

The 100gr ELD-VT at 2690fps beats any of the 6mm 103-110gr class at 2575fps, flatter, more impact velocity, less wind drift.

I’ll put it this way. I have not been off the steel yet with that 100gr ELD-VT, and I have only shot it from 700yds to 1k. My 8yr-old son, who never shot past 400yds before that day, went 5/6 at 1k, so it feels and behaves more like a 20-24” 6mm AR for me. The 6mm ARs I have shot have all been 20” and longer, simple neck-down from Grendel.

Grendel has more case capacity and more bore volume, so you can run it faster with less chamber pressure and get better results.
 
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