My new 6.5 Grendel

[65guys_steve]

A few months ago I added my third long range precision rifle to the stable, for local match shooting at ranges upto 600 yards. Just getting photos posted up now. My other two are bolt actions (338LM, 30-06), this one is a semi-auto built on an AR-15 platform. The project took over 7 months in the making to get all of the back order parts to come through the supply chain, completing the assembly of the parts, scope mounted and zeroed, and completion of optimal load development.

Below are the build specs. I’ve also included some photos of the rifle along with the optimal load 5 round group from my ladder tests which resulted in one bug hole on a 1" round circle target, with a single flyer resulting from an inconsistent trigger pull.

6.5 Grendel Build
Lower Receiver:

• PSA forged Mil-Spec-8625 Type 3 Class2 lower receiver, 7075-T6, Black Hardcoat Anodized (Laser Engraved with WaGuns.Org Logo)
• Daniel Defense Lower Parts Kit
• Geissele SSA-E Trigger (2 Stage, 3.5lbs 1st stage, 2.3lbs 2nd stage)
• M-16 Rifle Buffer
• Magpul PRS Stock
• Magpul BAD Lever

Upper Receiver: (Precision Firearms Custom Build – 6.5 Grendel Neptune)

• Precision Firearms CNC Machined Billet 7075 Flat Top Upper Receiver with Forward Assist, Port Cover, and Shell Deflector
• Precision Firearms Match Bolt Carrier
• 6.5 Grendel Bolt (9310 Steel)
• BCM Mod 3 Charging Handle Large Size
• Lilja Extreme Match stainless steel 24” Barrel 1-8” Twist, 11 degree Target Crown, Threaded for Brake
• Bead blast & Cerakote rifle barrel to Flat Black
• JP Enterprises JPTRE-5 Bennie Cooley Signature Series Compensator – Matte Black
• Midwest Industries T15G2 15” Free Float Hand Guard
• Harris BRM-S 6-9” Bipod

Scope:

• Bushnell Elite Tactical 3.5-21x50, Front Focal Plane with Horus H59 Reticle, 0.1 Mil Turrets
• Larue Tactical, LT-112 20MOA, quick disconnect Scope Mount

 

[Regalkismet]

Take a look at the phase V EBRV2.... It is much more durable than the Magpul Bad lever.... It's a one piece bolt release so there are no screws to worry about coming loose.... Nice rifle Btw.

 

[CrossHare]

Very nice ride indeed. This is next on my list.

 

[BLDTYLRY]

Chrono your load yet? Would like to see how fast a 24" barrel can run 123gr Amax's.

 

[65guys_steve]

My optimal accuracy load has the 123gr Amax leaving the muzzle of my rifle at 2525 FPS (temp 63.5F, station pressure 29.38, humidity 53%).

 

[bogeybrown]

My optimal accuracy load has the 123gr Amax leaving the muzzle of my rifle at 2525 FPS (temp 63.5F, station pressure 29.38, humidity 53%).

I absolutely PROMISE I am NOT ballbusting when I ask this, I am genuinely confused. My 18" (cut down Rem 1/12) .308 is running about 2550fps with factory 175gr SMK. I thought one of the the advantages of the Grendel was increased velocity, supersonic longer, etc.
I'm considering a Grendel upper to play around with on my Mini SASS, so I'm trying to get a better understanding of the external ballistics of the round.

If 2525 is where you've found your best accuracy, do you still feel as though you're getting the LR benefits of a 6.5 round?

As I said, honest questions, no agenda, not F'n with you, just really curious.

 

[bobke]

My current 'go to' loads with 123 Nosler CC's or Hornady 123 SST/AMax run 2550 in 20" barrel and 2650 in 24" Satern barrel. The very long 107 Sierra/108 Lapua's can be run up another 200+ fps with excellent results. Grendel is both capable at long distance and pretty load tolerant.

 

[bogeybrown]

Why was I thinking the Grendel ran a good bit faster than .308? Thanks for the info.

 

[338RUM runner]

The Grendel is just a necked down 7.62x39 case, not even close to a .308 or .260 in size. It is a very nice fit in a AR-15.

 

[bogeybrown]

Didn't mean to hijack. That is a beautiful rifle, and as I said I'm considering an upper. I knew it wasn't in the 260/6.5 Creed realm, just had a guy I worked with building Grendels going on and on about how it's outperforming the .308 out past 1000yds and was curious as to how it was doing that with a smaller projectile at comparable velocities.
To the OP, again, really nice rifle, and congrats on the build, that accuracy appears to be OUTSTANDING.

 

[65guys_steve]

I'm not offended by the question. I have a friend that shoots a Mega Maten .308, 22" barrel with a AA 51T Brake, using 175Gr. SMKs and I've had similar conversations regarding pros/cons of going either route. From an exterior ballistics standpoint the BCs and velocities are similar, so I would expect similar performance. In comparing between these two rifles and how it feels to shoot with them, I believe there are several ergonomic factors that favor the 6.5 Grendel. (1) The overall weight of the Grendel platform is less, The ammo and loaded cartridge is less. So carrying a rifle around with 70-100 rounds of loaded ammo in Eberlestock during a match day is easier on me. Additionally, manuevering the rifle on or around barriers during apractical/LR competition is easier to manage (2) Recoil is almost non-existent on my rifle as compared to friend's - This Grendel shoots like a lightly loaded .223. Even on the most challenging stages when I'm not squarely behind the rifle, I almost never lose sight picture when a round goes off so I can send quick follow up shots.

 

[bogeybrown]

I like the idea of the Grendel, in that I can get .308-ish performance out of a caliber I can shoot from a standard AR sized platform. It will be a toy for me more than anything. I have some pretty nice .308s, and one of them is destined for a caliber swap to one of the 6 or 6.5 platforms in the future once I figure out which one of those calibers it going to be.

THAT load is clearly optimum at 100, but do you shoot a different load for long range in the same way that .308 shooters may shoot 168s up to a certain range then switch to 175s?

 

[BLDTYLRY]

I'm running a 18" 264 ARP 1:8.5" Twist 5R and 123gr Amax's are at 2450fps with 25.5grs of XBR. Looks like I'm not losing too much to your 24" Barrel.

 

[ddavis]

Constructive Criticism:

I have the same rear bag. I shot with it just like you do standing on end for the longest time. Recently I switched to have the SBRM fully collapsed to the 6" height and the rear bag laying on its side parallel to the buttstock. It has helped my consistency greatly. Just something you might want to consider trying if your rifle allows it. Otherwise, really nice rifle.

 

[65guys_steve]

...do you shoot a different load for long range in the same way that .308 shooters may shoot 168s up to a certain range then switch to 175s?

I've exchanged notes with a number of other 6.5 Grendel shooters while I was getting the rifle together and the 123Gr. Amax's seemed to be the most popular for a number of reasons that I won't go into here. I ended up buying 10 boxes (1000 bullets) so until I work down my stash I'll be shooting these bullets for while. So far I'm very happy with the load given the intended objective of the rifle (local matches out to 600 yards). I did have the opportunity to take her out a month ago to 750 yards and was easily hitting a 66% IPSC steel target. It also allowed me to true up my ballistics drops and confirm the muzzle velocity based on actual bullet impact down range. I have other LR precision rifles in bolt actions, so when I want to go longer I'll use something else.

Constructive Criticism:

I have the same rear bag. I shot with it just like you do standing on end for the longest time. Recently I switched to have the SBRM fully collapsed to the 6" height and the rear bag laying on its side parallel to the buttstock. It has helped my consistency greatly. Just something you might want to consider trying if your rifle allows it. Otherwise, really nice rifle.

I actually have/use a number of rear bags. This particular bag I don't use all that much - seemed to be the right one for this day and this task.

 

[Primitive]

Do you really need a muzzle brake for that small of a round?

 

[svxwilson]

Do you really need a muzzle brake for that small of a round?

Need is subjective, I shot my Grendel without a brake on it before the brake showed up (mine is a similar set up PF 24", Bartlein). I also have the same JP brake. You can watch your impacts hit much easier with it. Follow up shots are faster. Although it is not necessarily needed, but I personally would rather shoot with it than without.

 

[Jon A]

My 18" (cut down Rem 1/12) .308 is running about 2550fps with factory 175gr SMK. I thought one of the the advantages of the Grendel was increased velocity, supersonic longer, etc.

Yeah, it's not the velocity you gain with the Grendel. It's that the various 123's have higher BC's than the .308 bullets commonly used (a little better than the 175, quite a bit better than the 168, etc). It's certainly not a huge gain, but any gain at all from the smaller round is something that makes it pretty attractive.

 

[Blacklab]

Sweet rifle! BTW I like how you keep your zero in the ten ring.

 

[LRRPF52]

I'm running a 18" 264 ARP 1:8.5" Twist 5R and 123gr Amax's are at 2450fps with 25.5grs of XBR. Looks like I'm not losing too much to your 24" Barrel.

I get 2460fps with 123gr Hornady factory ammo from my 16" AA MLGS Grendel, with 1/8 twist. I took it out to 1200yds on somewhat of a dare earlier this summer, even though I considered it really a 600-700yd gun. I'll be danged if I didn't make consecutive hits as fast as I could pull the trigger (there was literally no wind value...POI was POA). It changed my plans for how I'll be putting my IPSC steel out from now on.

I have a .260 Rem AR10, but I enjoy shooting the Grendel more due to light recoil, easy handling, especially for such a lightweight carbine. Think M4 with totally different reach and energy downrange.

 

[[email protected]]

What is the max load for your 123 gr and XBR 8208 combo?

 

[65guys_steve]

I had go back to my notes to look up ladder test results. My max load I tested with IMR 8208 XBR and 123 gr. Amax was 28.5 grains of powder. I saw no pressure signs on the brass so it seem like a safe load and I could have continued to go higher, while compacting the powder with the bullet. However, I saw no reason to go higher because I already found a good accuracy node and I was happy with the velocities I was getting.

 

[LRRPF52]

28.5C of 8208 XBR is the max published load by Hodgdon's with the 123gr SMK, and most people stop at 28.5gr with the 123gr Lapua, A-MAX or SST. Hodgdon's lists 50,000 psi with that load and the 123gr SMK.

If you want more velocity, look at CFE or AA 2520, which are fine ball powders. A lot of hi-power competitors like 8208 because as an extruded powder, it seems to be much more temp-shift stable compared to TAC and other fine ball powders.

Pressure signs on brass are more of a 2nd line of defense for me, as I look to the chronograph first for pressure signs when developing a load using a pressure/accuracy ladder. When I see erratic spikes out of a predictable velocity increase curve, I have reached a maximum for my system. I usually see about 25-35fps per every .2gr of 8208 XBR. Here's a graph showing a pressure ladder test where you can clearly see when things started to get erratic. One string isn't enough to show a trend, so I always run at least 3 batches of the same ladder loads to establish accuracy nodes more than anything.



Notice what happened at 29.8gr, and also notice that a 34fps increase picked up again between 30.2-30.4grs. I also started to see a flattening of primers, then a little ejector extrusion somewhere in those top 4 charge weights IIRC. When I look in my 6.5 Grendel Reloading Handbook, Hodgdon's has data for 8208 XBR and the 100gr NBT.

They're showing 30.8C as the max load with 2732fps mv from a 24" barrel with a chamber pressure of 47,600 psi. I have a 16" barrel. If I had gone up to 30.8gr, it looks like I would have reached that mv as well.