6mm max

[Yondering]

Ogive length .740"
OAL cartridge 2.250"

2.250-.740= 1.510

Grendel case length: 1.520
ARC case length: 1.490

The cartridge wasn't intended for commercial release in the beginning and the projectile design for the original customer required what they required and everything else followed suit.

I think what you meant to say is that Hornady chose to offer a specific bullet that didn’t work at the minimum possible magazine length restriction. Which conveniently “required” them to develop a “new and never been done before!” cartridge that is functionally identical to what a lot of people were already using and had already put their own names to.

Do you really think Hornady would have just released a commercial 6mm Grendel under their own name without doing something to make it proprietary? The goal was always to do their own “new” thing, whether it was needed or not.

 

[Yondering]

What bullets? Chances are I've tried them.
Just went and looked, 110SMK and 112 Matchburners fit with the ogive just past the neck at 2.26" OAL. If you have mags that allow 2.3" (as you should with this type of round) they both fit with plenty of wiggle room.

Exactly. It’s funny how “tens of thousands of hours” of development were expended but somehow nobody could figure that out… Of course they did; they knew exactly what they were doing even if some of the lower people in that totem pole may not have understood the real reasons for pushing a specific combo.

 

[LRRPF52]

Ogive length .740"
OAL cartridge 2.250"

2.250-.740= 1.510

Grendel case length: 1.520
ARC case length: 1.490

The cartridge wasn't intended for commercial release in the beginning and the projectile design for the original customer required what they required and everything else followed suit.

Is there a particular reason 2.260” isn’t used, and 2.250” is referenced above?

2.260” has been the standard AR-15 magazine-based COL limit for 66 years, and is the listed Hornady COL for 6mm ARC as well.

2.260” - .740” ogive = 1.520"

Grendel case length = 1.520"

Looks like a .740” ogive fit perfectly for the existing case.

The other interesting thing I noticed in one of the interviews with Hornady engineers was that the customers did testing with Hornady using several 6.5 Grendel carbines in place of their normal SR-25 pattern rifles. This was to fill the roles both in and out of the house, where elusive targets needed to be engaged at distances that exceeded the capabilities of 5.56 77gr, extending into the supersonic reach territory of the SR-25s, but not wanting the bulk/weight/limited magazine depth/lack of maneuverability in the house from the large frame rifles.

After going through the various scenarios, the customers were asked if there was any instance where they would have preferred a 7.62 NATO larger frame rifle vs the AR-15 small frame 6.5 Grendel, and the answer was unanimously “no”. Each end-user would take the 6.5 Grendel carbine vs their large frame rifles.

Then Hornady stated they could make it better.

My question is, why not just develop a 107-110gr 6.5mm with longer boat tail and optimized ogive and tip to get the BC into the mid-high .5xx G1 region?

When I look at 107gr SMK and 110gr PPU 6.5 Grendel performance real-world on-target, I’m not seeing a huge difference between it and 6mm AR, though there are benefits to the mid-.5xx BC bullets for wind drift at distance. Trajectories are about identical out to 800yds with bullets that are relatively old in design compared to the newer 6mm 105-109gr class.

Seems like it would be much easier to leave the brass alone, and work the projectile development if you want an even better wind-bucking lighter 6.5mm bullet. The Sierra advertised BC on the 107gr SMK is underrated as well, with Litz putting it at .462 G1 BC/.230 G7.

Basically a lengthening of the 107gr SMK with an A-MAX/ELD-M or A-TIP secant ogive with a little more weight would put it into the same BC class as the 103-109gr 6mms, and it can be pushed a little faster due to piston area/bore volume without even toeing the SAAMI MAP.

 

[Ledzep]

I think what you meant to say is that Hornady chose to offer a specific bullet that didn’t work at the minimum possible magazine length restriction. Which conveniently “required” them to develop a “new and never been done before!” cartridge that is functionally identical to what a lot of people were already using and had already put their own names to.

Do you really think Hornady would have just released a commercial 6mm Grendel under their own name without doing something to make it proprietary? The goal was always to do their own “new” thing, whether it was needed or not.

Guy on internet repeatedly tells engineer that helped develop cartridge why/how it was developed in the face of why/how it was developed. Classic.

Is there a particular reason 2.260” isn’t used, and 2.250” is referenced above?

2.260” has been the standard AR-15 magazine-based COL limit for 66 years, and is the listed Hornady COL for 6mm ARC as well.

2.260” - .740” ogive = 1.520"

Grendel case length = 1.520"

Looks like a .740” ogive fit perfectly for the existing case.

.....

My question is, why not just develop a 107-110gr 6.5mm with longer boat tail and optimized ogive and tip to get the BC into the mid-high .5xx G1 region?
...

Because of the magazines being used by the companies submitting rifles. And again, running the ogive start at the case mouth causes problems both for manufacturing and for the end user.

The 106 TAP/A-tip is in the upper .5's G1. Personally, I'd like to see 109's and a new ELD-X replace 108's and 103's but we'll see if/when the time is right for that. Over my pay grade.

V/R
Miles N.

 

[TonyTheTiger]

106 TAP/A-tip was the main driver, but there are others. Good for you if you can make them work. It was tested across several mfg. barrels, rifles, and magazines and we found issues that weren't acceptable for mass-scale ammunition production and the end results in the field. We've got tens and tens of thousands of rounds sunk into testing this. For one guy with one rifle to get everything tuned in with reloads, you have a lot of options available to you. If you're issued a rifle and ammunition, you don't.

It's similar to the .224 Valkyrie and 88-90gr projectiles. You can barely fit them at magazine length. Some people can make them work, but the bulk of factory ammo "sucks". Then, *magically* when you seat them long and/or in a bolt gun they hammer.... It's not the components that suck, it's the arrangement. When all you do is hand-load for a rifle that's one thing, when you have to produce accurate factory ammunition for an array of factory rifles there are trade-offs that happen that chip off the peak of what is possible to a skilled handloader with a custom rifle, but make the overall system function much better for the masses. Another .260 vs. 6.5 Creedmoor debate. At the end of the day, the SAAMI spec. solution functions better and gives more consistent results across a spectrum of rifle/barrels.

I have no experience with the 106 TAP, so you win there. Seems like you have some access to whatever happens behind the curtain, and I don't. I'll also admit/agree that a handloader has more flexibility in making things work. So I guess I have nothing left to argue about.
Carry on then.

 

[TonyTheTiger]

View attachment 8246223

So nothing for long range target use?

 

[Ernest 5.56]

So nothing for long range target use?

Has to be used north of the equator for long range. You lose alot of velocity when the bullet spins backwards south of the equator.

You mean ELR? Which aspect are you referring too? It's grrrrreat!

 

[FredHammer]

View attachment 8229635

Test Barrel: Bartlein 24” Twist: 1/8 Tested to SAMMI Standards in Socorro, NM at EMRTC.
View attachment 8229636

#21 - 100gr Sierra SBT BC listed as .496. Sierra site lists .419 for that velocity bracket. I checked manufacturer listed BCs of other bullets on this table and they seem on par, except #21. Must be an error. Also, running some of these bullets on 4DOF app (With the right BCs) I'm finding approx 1.8-2 mil less drop at 900yds than the 77SMK 5.56.

 

[LRRPF52]

#21 - 100gr Sierra SBT BC listed as .496. Sierra site lists .419 for that velocity bracket. I checked manufacturer listed BCs of other bullets on this table and they seem on par, except #21. Must be an error. Also, running some of these bullets on 4DOF app (With the right BCs) I'm finding approx 1.8-2 mil less drop at 900yds than the 77SMK 5.56.

I noticed the same.

One thing that always gives me pause in a gas gun with rebated rims is increasing the chances of bolt over-base malfs, but the difference between .378” and .390” is probably negligible in practice with this cartridge.

 

[Lightning8]

Is there a particular reason 2.260” isn’t used, and 2.250” is referenced above?

2.260” has been the standard AR-15 magazine-based COL limit for 66 years, and is the listed Hornady COL for 6mm ARC as well.

2.260” - .740” ogive = 1.520"

Grendel case length = 1.520"

Looks like a .740” ogive fit perfectly for the existing case.

The other interesting thing I noticed in one of the interviews with Hornady engineers was that the customers did testing with Hornady using several 6.5 Grendel carbines in place of their normal SR-25 pattern rifles. This was to fill the roles both in and out of the house, where elusive targets needed to be engaged at distances that exceeded the capabilities of 5.56 77gr, extending into the supersonic reach territory of the SR-25s, but not wanting the bulk/weight/limited magazine depth/lack of maneuverability in the house from the large frame rifles.

After going through the various scenarios, the customers were asked if there was any instance where they would have preferred a 7.62 NATO larger frame rifle vs the AR-15 small frame 6.5 Grendel, and the answer was unanimously “no”. Each end-user would take the 6.5 Grendel carbine vs their large frame rifles.

Then Hornady stated they could make it better.

My question is, why not just develop a 107-110gr 6.5mm with longer boat tail and optimized ogive and tip to get the BC into the mid-high .5xx G1 region?

When I look at 107gr SMK and 110gr PPU 6.5 Grendel performance real-world on-target, I’m not seeing a huge difference between it and 6mm AR, though there are benefits to the mid-.5xx BC bullets for wind drift at distance. Trajectories are about identical out to 800yds with bullets that are relatively old in design compared to the newer 6mm 105-109gr class.

Seems like it would be much easier to leave the brass alone, and work the projectile development if you want an even better wind-bucking lighter 6.5mm bullet. The Sierra advertised BC on the 107gr SMK is underrated as well, with Litz putting it at .462 G1 BC/.230 G7.

Basically a lengthening of the 107gr SMK with an A-MAX/ELD-M or A-TIP secant ogive with a little more weight would put it into the same BC class as the 103-109gr 6mms, and it can be pushed a little faster due to piston area/bore volume without even toeing the SAAMI MAP.

I always feel like I am lobbing rounds at the targets with my 65 Grendel - it works but seems like a mortar. Agree that a 107ish high BC 6.5 projectile would help.

 

[LRRPF52]

I always feel like I am lobbing rounds at the targets with my 65 Grendel - it works but seems like a mortar. Agree that a 107ish high BC 6.5 projectile would help.

From the shorter barrels shooting 120-130gr, there certainly is that .308 Win 175gr trajectory feel, only you have almost no recoil and just watch your own rounds go in without needing a spotter.

Even with 12” Grendel, the 107gr SMK and 110gr PPU factory ammo are freaking flat. The funny thing is, I could not get the PPU to shoot under 2.75” at 100yds even with my Lilja 17.6” Grendel, let alone the 12”. I kinda wrote-off the 110gr as 400yd blaster ammo at best.

Then I thought, “What the heck." and tried it from the 12” Faxon pipe at 780yds 3/3 hits, then took it to 900yds on a 12” plate, 1st-round hit. Go figure, but I was tickled. Impact isn’t anywhere near as loud as 123gr ELD-M though.

I love how 123gr sounds when it hits. I love how flat 107-110gr is. Best way to step it up is barrel length, and I have a 22” Grendel but I just never shoot it because I’ve been chasing the smallest blaster possible, with the best effects at distance.

6mm is great for that flat trajectory, but momentum on-target sucks, no matter what the programs say the ft-lbs are. You just don’t see much splash, nor do you hear it that well outside of clean, calm conditions. I’ve noticed this with 25-26” barreled 6mm BRs, 6mm Dashers, 6 CMs, 6x47s, doesn’t matter. Fun cartridges to shoot with no recoil, but they just don’t do it for me.

If I could find a way to spit out a 7mm 195gr EOL with Grendel recoil that fits in the AR-15, I would have already. I love the sound of 180-195gr 7mm impacting steel at distance, but I’ve never been able to spot my own hits with those either.

 

[Ledzep]

@LRRPF52 I misread your earlier comment. I thought we were talking 6mm but you were wanting a 107gr style 6.5mm in the mid/upper .5's G1.

I don't think you'll have an easy time getting that to happen, especially in the 6.5 Grendel envelope. You might get mid/upper .4's with a 100gr class bullet, though. Boat tail gains you BC but it's got diminishing returns in BC growth, at the same time it gets harder and harder to produce (good bullets) the longer the BT is. Longer ogive will get you some love, but there's a limit to what you can do and you need to keep a certain ratio of bearing surface or risk in-bore yaw. If you go too far with CG to the rear (leaving air cavity in the front), you run into sensitivity problems.

Long ogive, long BT, short bearing surface, stuffed all the way to the case mouth is a recipe for a very picky/erratic package.

 

[PinesAndProjectiles]

I’ve got to dig up some data as it’s been a while since I’ve tinkered with it, but I think this is right in line with 6x6.8 velocities.

And I can take 6.8 brass and neck down in one stroke so it isn’t a huge time suck when prepping brass.

 

[LRRPF52]

@LRRPF52 I misread your earlier comment. I thought we were talking 6mm but you were wanting a 107gr style 6.5mm in the mid/upper .5's G1.

I don't think you'll have an easy time getting that to happen, especially in the 6.5 Grendel envelope. You might get mid/upper .4's with a 100gr class bullet, though. Boat tail gains you BC but it's got diminishing returns in BC growth, at the same time it gets harder and harder to produce (good bullets) the longer the BT is. Longer ogive will get you some love, but there's a limit to what you can do and you need to keep a certain ratio of bearing surface or risk in-bore yaw. If you go too far with CG to the rear (leaving air cavity in the front), you run into sensitivity problems.

Long ogive, long BT, short bearing surface, stuffed all the way to the case mouth is a recipe for a very picky/erratic package.

Tracking all that, and it came across as though you were talking about 6mm. Hybrid ogive really helps in that regard though, and has already been proven to work with long BT, long ogive, short relative bearing surface projectiles.

110gr is still just as flat in my experience as 107gr. With 6.5mm, it also leaves options open for tracer burn time, M855A1-style EPR (6.5mm EPR already exists), and room to play with projectile weight that simply does not exist in 6mm.

The 103-109gr 6mm definitely are flat though, with excellent wind deflection characteristics. Current 105-109gr 6mm will provide a little bit more supersonic reach than legacy 107gr SMK 6.5mm by about 150yds if both are fired at the same mv.

It would be nice to have renewed efforts in magazine development. Bill Alexander did everything in his power to ensure reliable, quality magazines, and the industry kinda worked around him just to make sales.

Out of the gate, he specified curved magazines for the 17rd in the 2000s, and one of the initial vendors sent him a pallet of straight mags. The straight mags didn’t work of course, and were rejected. Instead of recycling those mags, they were sent to 44mag.com and Midway USA to be sold as 6.5 Grendel mags. They would work fine with 7-10rds depending on barrel extension and feed ramp geometry, but people experienced the same problems with trying to load them full. No customer should have ever known they existed, let alone be able to buy one, but they became mass-produced items.

The curved 25rd mags work great for me and have for many years. I de-edge, blend, and polish my feed ramps, and make sure none of my bolts have an ejector that can impinge in right side feed presentation. Across 7 different 6.5 Grendels I have, I just don’t have feeding, extracting, or ejection issues.

From a manufacturing standpoint, we’re in a place where we should have a repeatable and consistent magazine body that will allow 2.280” COL with room to spare for field conditions. I know all my old school CPD and old/new ASC mags will do that. Elanders don’t allow any more than 2.260”, and are probably the source of your previous constraints you mentioned.

 

[Ernest 5.56]

Tracking all that, and it came across as though you were talking about 6mm. Hybrid ogive really helps in that regard though, and has already been proven to work with long BT, long ogive, short relative bearing surface projectiles.

110gr is still just as flat in my experience as 107gr. With 6.5mm, it also leaves options open for tracer burn time, M855A1-style EPR (6.5mm EPR already exists), and room to play with projectile weight that simply does not exist in 6mm.

The 103-109gr 6mm definitely are flat though, with excellent wind deflection characteristics. Current 105-109gr 6mm will provide a little bit more supersonic reach than legacy 107gr SMK 6.5mm by about 150yds if both are fired at the same mv.

It would be nice to have renewed efforts in magazine development. Bill Alexander did everything in his power to ensure reliable, quality magazines, and the industry kinda worked around him just to make sales.

Out of the gate, he specified curved magazines for the 17rd in the 2000s, and one of the initial vendors sent him a pallet of straight mags. The straight mags didn’t work of course, and were rejected. Instead of recycling those mags, they were sent to 44mag.com and Midway USA to be sold as 6.5 Grendel mags. They would work fine with 7-10rds depending on barrel extension and feed ramp geometry, but people experienced the same problems with trying to load them full. No customer should have ever known they existed, let alone be able to buy one, but they became mass-produced items.

The curved 25rd mags work great for me and have for many years. I de-edge, blend, and polish my feed ramps, and make sure none of my bolts have an ejector that can impinge in right side feed presentation. Across 7 different 6.5 Grendels I have, I just don’t have feeding, extracting, or ejection issues.

From a manufacturing standpoint, we’re in a place where we should have a repeatable and consistent magazine body that will allow 2.280” COL with room to spare for field conditions. I know all my old school CPD and old/new ASC mags will do that. Elanders don’t allow any more than 2.260”, and are probably the source of your previous constraints you mentioned.

Geissele did make improved 6arc mags but I don't know what aspects were improved

 

[steve123]

From the shorter barrels shooting 120-130gr, there certainly is that .308 Win 175gr trajectory feel, only you have almost no recoil and just watch your own rounds go in without needing a spotter.

Even with 12” Grendel, the 107gr SMK and 110gr PPU factory ammo are freaking flat. The funny thing is, I could not get the PPU to shoot under 2.75” at 100yds even with my Lilja 17.6” Grendel, let alone the 12”. I kinda wrote-off the 110gr as 400yd blaster ammo at best.

Then I thought, “What the heck." and tried it from the 12” Faxon pipe at 780yds 3/3 hits, then took it to 900yds on a 12” plate, 1st-round hit. Go figure, but I was tickled. Impact isn’t anywhere near as loud as 123gr ELD-M though.

I love how 123gr sounds when it hits. I love how flat 107-110gr is. Best way to step it up is barrel length, and I have a 22” Grendel but I just never shoot it because I’ve been chasing the smallest blaster possible, with the best effects at distance.

6mm is great for that flat trajectory, but momentum on-target sucks, no matter what the programs say the ft-lbs are. You just don’t see much splash, nor do you hear it that well outside of clean, calm conditions. I’ve noticed this with 25-26” barreled 6mm BRs, 6mm Dashers, 6 CMs, 6x47s, doesn’t matter. Fun cartridges to shoot with no recoil, but they just don’t do it for me.

If I could find a way to spit out a 7mm 195gr EOL with Grendel recoil that fits in the AR-15, I would have already. I love the sound of 180-195gr 7mm impacting steel at distance, but I’ve never been able to spot my own hits with those either.

Looks like a 25 cal Grendel based wildcat was the answer all along if one wanted the highest BC combined with that thwack you prefer.

I wonder of anyone did this yet? Maybe using the heaviest 25's the ogive is too long to work at 2.260??

 

[357Max]

I noticed the same.

One thing that always gives me pause in a gas gun with rebated rims is increasing the chances of bolt over-base malfs, but the difference between .378” and .390” is probably negligible in practice with this cartridge.

FWIW - I've had no issues at all running .378 bolt with .422 on my hybrid Valk from PRI mags. 77SMK has about the worst bc for that class bullet. The valk Loves 77 RDF's at 2920-2950. BC is .228 G7 / .454 G1
This is 24 Nosler formed to 224 Valkyrie, running 5.56 bolt. Has 32.7 h20 once fire formed using 69RMR's

Wildcat I'm working on now uses 400 Legend brass, .422 bolt/ .441 body. 224 for 77-90 gr with 37.3 h20 case cap. Winter project.

 

[LRRPF52]

Geissele did make improved 6arc mags but I don't know what aspects were improved

I saw the Soldier Systems article indicating Geissele developed a 6mm ARC magazine, with a picture of a longer, straight 20rd.

There was a lot of activity with several manufacturers jumping on the 6mm ARC bandwagon because it was trending, but I didn’t see any evidence of a new magazine. Most appeared to be 6.5 Grendel Elanders with 6mm ARC markings, which have limited COL allowable.

This would explain Hornady’s pressure to reduce the COL during development, and set the shoulder back, because my Elander mags won’t allow anything over 2.260”, and manufacturing variances have to be taken into account so that factory ammo doesn’t ever bind up in the magazine. You have to check more than the top 2 cartridges when seeing if your magazine will work with your COL.

I learned that the hard way at an international Sniper match in Finland with my .260 Rem LR-260. I could get 15rd in a PMAG before they would bind-up with the more curved cartridge stack down in the magazine cocking the cartridges so that the actual overall length in practice was from the meplat to the edge of the rim, not the flat surface of the head. I had set my COL to over 2.800” with 130gr VLD in .260 Rem because my dummy cartridge easily fit at the top of the mag with clearance. That was with Gen 1 7.62x51 PMAGs.

Hornady should never have been in the position to have to deal with magazines that weren’t ideal, then try to shoehorn into that. These things show how important total ownership is for the technical data and dimensions when working on a new cartridge.

The magazine, ammunition, and rifle manufacturers need to sit down together from the start and spec everything out initially, with working relationships that constantly communicate with each other, driven by a single personality in leadership who understands and holds to the vision for the overall product set.

Trying to piece it all together will lead to compromises.

 

[LRRPF52]

Looks like a 25 cal Grendel based wildcat was the answer all along if one wanted the highest BC combined with that thwack you prefer.

I wonder of anyone did this yet? Maybe using the heaviest 25's the ogive is too long to work at 2.260??

Bill was looking at .257” in the beginning (along with .338 if I recall), but the projectile selection was really limited. 25 cal is actually pretty ideal for bore diameter/case diameter.

Unfortunately, the new 131-135gr .257” high BC bullets won’t get anywhere close to mag length COL in the AR-15 frame unless you bury them into the powder column past the SNJ.

L-R: 6.5mm 140gr Berger, 140gr A-MAX, Middle: 131gr ACE .257”, 6mm AR, 123gr SST

We need a 2.5” COL capable receiver set and magazines. The new VLD quarter bores from a 2.500” COL AR-15 action would put the AR-10 to bed. Even when fired at only 2350fps from a short barrel, the 133gr Berger, 134gr Hornady, and 135gr Berger are amazing. G7 BCs are in the .3s

133gr .315 / G1 .613
134gr .325/ G1 .645
135gr .334/ G1 .650

No need to mess around with a .473” case either, unless you wanted to do something off a BR. Keep it small with a short propellant column. 25 GT would be ideal for speed, but requires AR-10 action. Yeah, I’ve been looking at 25 cals since my grandpa introduced me to reloading. He was a huge fan of the 257 Roberts. I’ve always liked 25-06 and 25 WSSM as well, but we just didn’t have any high BC bullets to compete with either the 6mms or 6.5s, but that has changed now ever since the 131gr Ace (made by Sierra for Blackjack).

But even from a .441” sized case, the 130gr class of 25 cals would spank the steel hard, would kill large game, and would be low recoil. It would feel like shooting Grendel, but have downrange performance more like 6.5CM. You hit 1 mil of wind drift at 600-700yds with the 25 cals, depending on elevation. 900ft-lbs at 675yds at lower altitude if shot at 2500fps mv, 825yds/900ft-lbs at one of my main shooting locations.

 

[357Max]

25 GT would be ideal for speed, but requires AR-10 action.

I did the 25 shuffle in my head and landed on 25 x 47 Lapua to be about ideal for the AR10. It's on my short list to build.

 

[LRRPF52]

FWIW - I've had no issues at all running .378 bolt with .422 on my hybrid Valk from PRI mags. 77SMK has about the worst bc for that class bullet. The valk Loves 77 RDF's at 2920-2950. BC is .228 G7 / .454 G1
This is 24 Nosler formed to 224 Valkyrie, running 5.56 bolt. Has 32.7 h20 once fire formed using 69RMR's

View attachment 8247837

Wildcat I'm working on now uses 400 Legend brass, .422 bolt/ .441 body. 224 for 77-90 gr with 37.3 h20 case cap. Winter project.

I bet Nosler brass holds up better than Federal.

Good to know on rebated performance. Bolt thrust will be what it is regardless of the head diameter, but smaller case heads of course allow for more lug root material.

That 400 Legend will be nice to wildcat off of since there isn’t a neck process done to the brass yet, and its body is slightly larger than 6.8 SPC, though it has the .422” head. 400 Legend is .422/.440 whereas 6.8 SPC is .422/.421.

I was looking at a Ruger AR-15 chambered in 450 Bushmaster at Sportsman’s the other day, when something caught my eye. The bolt was made from some type of exotic material, so I looked on their site for more information.

Ruger 450 Bushmaster AR-15 Product Info

• To support the large case head of .450 Bushmaster ammunition, the .450 Bushmaster bolt is engineered with tapered lugs and machined from a high-strength superalloy.

450 Bushmaster has a .473” head/.500 body that tapers to .482”, but SAAMI MAP is only 38,500psi.

 

[LRRPF52]

I did the 25 shuffle in my head and landed on 25 x 47 Lapua to be about ideal for the AR10. It's on my short list to build.

That would be a good cartridge for the SFAR, with someone who knows what they’re doing controlling the barrel, chamber, gas port location, diameter, and gas block.

Would be sick in a short package suppressed. Hard to beat the Lapua SRP brass as well. Janne P. and crew knocked it out of the park with that cartridge really.

 

[FredHammer]

@LRRPF52 - I distinctly recall the "tink" vs the "smack" compring 5.45X39 and 5.56. I bought a Polish Tantal and 10K of rounds. Shot on steel at 300-400yds. I was woefully unimpressed by the amount of energy that 5.45X39 had that I sold the gun and ammo. The 5.56 hit with way more authority and I could see the plate swing a bit. Lots more accurate delivery system of the 5.56 too, LOL.

 

[steve123]

That would be a good cartridge for the SFAR, with someone who knows what they’re doing controlling the barrel, chamber, gas port location, diameter, and gas block.

Would be sick in a short package suppressed. Hard to beat the Lapua SRP brass as well. Janne P. and crew knocked it out of the park with that cartridge really.

I was one of the first to get on the 6x47L bandwagon. Earlier today when I was cleaning the garage I saw one of my ladder test targets at 320Y using Berger hybrid 105gr which has three shots touching. I do ladders in .1 grain increments so the difference between them is .3 grain for all three shots!

Still have the brass with tight primer pockets and some have over 25 firings on them.

Been shooting 6mmBR but might give 25x47L a go on my next Mausingfield barrel.

Fun info you gave and I too would like to see that 25 cal 2.5" specialty AR done correctly like you described.

Thanks.

Oh, clears throat, 6mmMax thread.

 

[Yondering]

Hornady should never have been in the position to have to deal with magazines that weren’t ideal, then try to shoehorn into that. These things show how important total ownership is for the technical data and dimensions when working on a new cartridge.

While that's true, it's only part of the story. Keep in mind that they chose to design a bullet that didn't previously exist but that wouldn't fit a standard 6mm Grendel within that shortest mag constraint. Everyone else out there already shooting a 6 Grendel of some sort was fine even with 110gr bullets, but Hornady's own bullet design meant they "had to" shorten the case? It's not hard to see that longer ogive design was most likely presented with the goal of creating their own unique cartridge to fit it.

It's no surprise to hear from some engineer who didn't see the bigger picture. But the way companies like that work, marketing is involved before and after engineering. The marketing guys are always looking for an opportunity, and they're not stupid; there's zero chance they didn't see development of the 6 ARC as an opportunity to sell their own special bullets and make a new cartridge that nobody else had. Might as well hit two birds at once; they wouldn't have been doing their jobs if they hadn't.

 

[LRRPF52]

I have yet to see a company that’s willing to spend millions being an advocate for someone else’s design, though here are the 2 closest ones I can think of:

* 300 Whisper re-labeled by AAC, then Remington’s acquisition of AAC, with the sole intent of reaping all the financial benefits of JD Jones’ cartridge and developmental work.

* Hornady taking 6.5 Grendel to SAAMI and supporting it with great factory ammo all these years when they recognized that it turned the AR-15 into a legitimate target and hunting rifle. 6.5 Grendel is the only small company-originated cartridge that achieved SAAMI and CIP standardization with over 100 factory loads, that include everything from steel case to Federal Gold Medal Match.

Most of the semi-popular AR-15 cartridges developed over the past 20 years will never reach a fraction of those achievements.

With the big name manufacturers, Hornady has really risen above the legacy names (Federal, Remington, Winchester) in developing successful cartridges with market traction, then supporting those cartridges with factory ammo. We’ve also seen rifle-builders respond with large lists of SKUs in Hornady’s chamberings when you look at 6.5 Creedmoor, then 6.5 PRC, 300 PRC, and 7mm PRC. Hornady didn’t really have their own baby though that would be popular/successful in the AR-15 frame. They’ve been making great ammo for 6.5 Grendel, 300 Whisper, 6.8 SPC, and even tried to do their own with 6mm Hagar, but that didn’t stick due to limited ogive length. 6mm ARC gave them their opportunity to have an AR-15/Hornady baby that was also a direct DoD customer requirement with genuine performance parameters to be met.

The culture you see in the legacy big brands is more about guys in suits who still think about the American Rifleman / Guns & Ammo old school print media model, where they knew they could rely on marketing hype (they control) through funded ads in the gun magazines, with shill authors who will write up a shining review of their latest cartridge, rifle, pistol, scope, etc. They have largely migrated that model over to Digital media, but don’t have the genuine feel/trustworthiness that the newer shooters are looking for. The decision-makers are not like most of us, but instead care about that top dollar and huge pieces of real estate on planned golf or country club communities with their manicured hair, finger nails, facials, and expensive attire. You can smell them a mile away at SHOT Show and realize immediately they aren’t people you’ll ever be neighbors with.

Unless it was a massive turd that the public immediately got bitten by, the big brands could sell practically anything and generate artificial hype that was then confirmed with sales. “See, that new _______ is a great product. Did you see Homer Shillstein’s article on it? He said it was a sub-MOA sure shot!” They still do that because their main driver for rifle sales is hunting season.

Walk over to Hornady and you immediately see you’re dealing with guys that are into reloading, chasing performance, trying to help shooters with better products that the layman can access, use, and benefit from. They’re not looking down their nose at you in their Armani suits, or strutting away with Wayne LaPierre to the next insider industry-only hidden booth somewhere.

With that all said, I think Hornady is the cartridge brand of the early 21st Century to watch, the ones who are setting the pace. Look at the imitations that have come out since from the big boys, as well as the old ideas doubling down and flopping.

 

[LRRPF52]

The 6mm Max appears to be what 5.56 should have been though. If their numbers are legitimate and not baked, it looks like you can load as many rounds in the same size mags more or less, spit a 55gr at original SCHV velocity objectives, then also shoot 100gr to 2750fps from a 24” barrel. One constraint they have described is the need for magazines that support 2.300” COL, which is a manufacturing tolerance challenge when wanting to stay in the confines of existing AR-15 magazine wells. When tolerance stacks on the lower and higher end of mag wells and magazines, you get mags that won’t drop free, even if the mags were built perfectly.

I saw that with some of the initial pre-production Elanders for 6.5 Grendel, and they barely support 2.260” COL. I tried them in all of my lowers that I had, and they all were a press-fit affair. I gave that feedback back to AA and it seems to have been dialed-in when Elander started cranking them out.

I kind of like the PRI 6.8 mags construction for the front walls with the single layer of interlocking dovetails, vs layered stampings that are then spot-welded over each other. Polymer mags won’t support longer COL because of material thickness.

 

[Ernest 5.56]

The owners said they are going to take the cartridge to SAAMI at some point.

I would love to see a full on cartridge war between 6mm Max and 6mm Arc the war that never happened with 224 Valkyrie

 

[FredHammer]

The owners said they are going to take the cartridge to SAAMI at some point.

I would love to see a full on cartridge war between 6mm Max and 6mm Arc the war that never happened with 224 Valkyrie

Fuck Bro! I’m ready to FAFO the 6max! Wish they’d answer their damn phones though!

I will compare to 5.56 77SMK M262. Since the Max will use same everything except barrel. Ballistics wise, yeah 6ARC smokes it, probably 65Gren too, but with all the silly ass BCGs & mags.

 

[knuckleballz]

Interesting read. I am ordering a couple more 220 thunderbolt AR15 barrels after reading this. currently running 30 grains of reloader 15.5 and 77 grain bullets at 3200fps that is really easy on the hagar hornady brass. Thought of ordering a 6 hagar to use up 87 vmax and 90 tgk and 100 tgk since I have lots of brass. I will be following this 6mm Max to see how it progresses

 

[steve123]

Speaking of the 300PRC...I told one of the higher up's at the Hornady booth at ShotShow at least a few years before 300PRC came out about my 30-375 Ruger Wildcat which is basically like 6mmAR as compared to 6mmARC. The old guy just looked at me funny and said they had no plans of doing anything like it.
And here we are.
But I can only take credit for the suggestion because a gunsmith named Glenn Pierce designed my reamer.

6mmMAX aye!

 

[FredHammer]

Talked to Brian of BC Precision Ballistics this morning. About 30 min convo. Dude was straight shooting. Very pleasant conversation and he backed it with solid data & knowledge. We kept the conversation to AR15 platform performance and I learned some good nuggets of knowledge. I am a skeptic and a value based critter and I'm very happy with the intel and pricing. Got an invite to go shoot down there in TX too! Can't wait!

 

[Ledzep]

While that's true, it's only part of the story. Keep in mind that they chose to design a bullet that didn't previously exist but that wouldn't fit a standard 6mm Grendel within that shortest mag constraint. Everyone else out there already shooting a 6 Grendel of some sort was fine even with 110gr bullets, but Hornady's own bullet design meant they "had to" shorten the case? It's not hard to see that longer ogive design was most likely presented with the goal of creating their own unique cartridge to fit it.

It's no surprise to hear from some engineer who didn't see the bigger picture. But the way companies like that work, marketing is involved before and after engineering. The marketing guys are always looking for an opportunity, and they're not stupid; there's zero chance they didn't see development of the 6 ARC as an opportunity to sell their own special bullets and make a new cartridge that nobody else had. Might as well hit two birds at once; they wouldn't have been doing their jobs if they hadn't.

Man... Some people must go through life never having the idea cross their mind that maybe they don't know everything...

AGAIN, it wasn't initially intended to be a commercial release. The design changes all were made months/years before we decided that it was viable for the commercial market and before marketing knew it existed. I distinctly remember the day that we took this to Jason's office and pushed for it as a commercial release because we (engineering team) had all used it and were so impressed.

You're wrong about this. Point blank. LRRP used 2 ounces of common sense and hit the nail on the head.

 

[Ape_Factory]

I swear I was shooting next to the OP at least a year ago, maybe even two, out at Bexar Community range. I remember you mentioning MV's in the 3400 or 3500 range and I think I might have moved down 4-5 tables after hearing you say that, LOL. All kidding aside, I do remember how excited you were at the results and wish I'd talked to you a bit more back then.

 

[Ernest 5.56]

 

[Ernest 5.56]

From SOLGW instaface

 

[OddBall]

Good groups. If results like that are common, that round could gain popularity quickly.

 

[FredHammer]

From SOLGW instaface

View attachment 8253084View attachment 8253086View attachment 8253087

Be nice to know barrel length & velocity.

 

[Lightning8]

I figured out what I want this cartridge for. A 22 Max wildcat. Neck it down and shoot 80ELD's at 2850 from a 16" barrel. I'm more interested in a (relatively) high BC .224 than a medium BC .243.

With the announcement of 22 ARC, I am even more interested in "22 MAX".

 

[Ernest 5.56]

Prototype 30rd duramag @ quantified performance

 

[Ernest 5.56]

6mm MAX – An ARBuildJunkie Q&A with Michael Russo – AR-15 News...

We spoke with Michael Russo, team shooter for Sons of Liberty Gun Works, about how his switch to 6mm MAX has improved his capabilities.

www.arbuildjunkie.com

 

[FredHammer]

Damn, they do take a different magazine than regular 5.56. How did I miss this up till now? I guess all I heard was being able to use existing BCG and mags...

 

[Ernest 5.56]

Damn, they do take a different magazine than regular 5.56. How did I miss this up till now? I guess all I heard was being able to use existing BCG and mags...

350 legend mags as that's the parent csse

 

[FredHammer]

350 legend mags as that's the parent csse

I know. It's just that this was glossed over I guess. So, can we buy a 6max barrel today?

 

[LRRPF52]

6mm MAX – An ARBuildJunkie Q&A with Michael Russo – AR-15 News...

We spoke with Michael Russo, team shooter for Sons of Liberty Gun Works, about how his switch to 6mm MAX has improved his capabilities.

www.arbuildjunkie.com

So he said that he and other competitors have experienced the following problems with 6mm ARC:

* Seized gas tubes from carbon fouling
* Broken extractors
* Cracked or sheared bolt lugs
* Feeding issues

I can’t speak to 6mm AR or 6mm ARC in high volume, but can with 6.5 Grendel. I’ve not only been shooting 6.5 Grendel since 2009, but typically have anywhere from 2-4 people bring them to DM courses throughout the year, where we shoot more rounds in 2-3 days/1-2 nights than you will in most gas gun competitions.

Dating back to 2012, there are LR shooting events I’ve helped spot and coach where guys’ positions with 6.5 Grendels looked like a Support-By-Fire gun team was getting after it, there was so much spent brass. There’s an event up in Idaho called BoomerShoot where we ran a 2-day precision rifle clinic, and on Day 3, people shoot 1200-1400 different explosive targets at LR for fun, so you can sit there all day and blast little 1 MOA boxes of reactive binary targets to your content at 375-700yds. That event favors a high round count. I’ve always taken a 6.5 Grendel or two to that event, as do several other people.

At least in Grendel, I have never experienced clogged gas tubes. That’s really weird that he’s seeing it in the 6mm ARC, but I just haven’t across 7 of my own Grendels, or anyone else’s that are shot in volume. Keep in mind for the past 6 years I’ve neglected most of my other Grendels and have really focused on the CLGS 12” suppressed. I’ve never shot it without the can once that stupid GayTF stamp cleared on my TBAC Ultra 5. We all know how hard CLGS suppressed can be on internals.

Key differences that I do when approaching a built are:

Chamber has to be right or the barrel doesn’t get installed into an upper. With companies that don’t have competent ownership or management, chambers are all over the map in this industry with every cartridge.
Feed ramps get de-edged, blended, and polished so there is almost no opportunity for meplats or shoulders to get scraped. I do this on 5.56 and AR-10s too.
Upper face is squared. Helps prevent imbalanced bolt lug load under pressure.
Gas port has to be correct or I don’t mess with the barrel. BTDT for other people with crazy port diameters that just make life hard on you.
Careful bolt selection. I’ve either used AA, PF, or the Monster Logo Utrabolts.
O-ring gets pulled if present and correct spring tension verified with insert.
Extractor lip gets tuned if the corner fangs are there.
Mags have to have uniform, correct angle feed lips.

For CLGS Suppressed, I’m using the Bootleg Adjustable Gas carrier and extra power carbine action/recoil spring, standard 2.9oz buffer.

Gun runs like a raped ape. I wouldn’t waste my travel time, ammo budget, and range time if it didn’t work. Imagine me making a fool of myself in front of attendees or my kids with a non-functional malf-o-matic with all these problems. It just doesn’t make sense for me to waste my time with something that won’t work.

Seems like there is more room to be done on getting 6mm ARC working with the Rifle/Ammo/Mag components. It isn’t the same as Grendel due to bore volume and ogive/neck geometry relative to the feeding interface with the feed ramps/extension, and feeding cone in the breech.

I’d be interested to know more specifics about the components these guys are having failures with in 6mm ARC, especially bolts and mags, as well as the types of ammunition they are using to cause the clogged gas tubes.

 

[PappyM3]

So he said that he and other competitors have experienced the following problems with 6mm ARC:

* Seized gas tubes from carbon fouling
* Broken extractors
* Cracked or sheared bolt lugs
* Feeding issues
….
I’d be interested to know more specifics about the components these guys are having failures with in 6mm ARC, especially bolts and mags, as well as the types of ammunition they are using to cause the clogged gas tubes.

From initial 6 ARC impressions I got from people, the early (maybe still?) Hornady factory loads were really dirty. That could easily explain clogged gas systems.

It also seems like 6 ARC prefers longer gas systems, but many barrel manufacturers are treating them like 5.56. Some like Wilson even using mid-length for an 18” 6 ARC barrel. Though apparently they’ve upped it to an intermediate length, but they still seems short.

Perhaps the extra force on the BCG with the short-for-cartridge gas systems is causing premature bolt wear (in addition to the bolt lug issues possible with this case head diameter when not using good quality bolts.

 

[Ernest 5.56]

I know. It's just that this was glossed over I guess. So, can we buy a 6max barrel today?

I messaged one of the owners he said store is going live mid November and barrels are expected to be in stock in December

 

[FredHammer]

I messaged one of the owners he said store is going live mid November and barrels are expected to be in stock in December

Welp, I'm applying my POW training now and trusting no dates and no times.

 

[CZ 527]

Sounds interesting. When & where will brass be available? Reality for me is the 6mm arc in my mini bolt action rifles will do as good or a bit better than the 6mm max. Still find the 6mm Max to be a contribution worth keeping an eye on at the very least. Think I seen this will be hitting the market by November 1st of what year.

 

[Ernest 5.56]

Sounds interesting. When & where will brass be available? Reality for me is the 6mm arc in my mini bolt action rifles will do as good or a bit better than the 6mm max. Still find the 6mm Max to be a contribution worth keeping an eye on at the very least. Think I seen this will be hitting the market by November 1st of what year.

Got pushed back to December I believe