CMMG 6.5 Grendel

[LRRPF52]

There's a major void in the market CMMG seems to be filling as well with this, not related to the frame or BCG size, but their SKUs.

They have complete pistols with 12.5" MLGS, ready to go, which is a nice option for those who want a Grendel SBR or pistol made under one roof.




Depending on what their lug lengths are, I'm guessing you could use a working pressure of about 56,000psi with this Bolt, extension, and barrel tennon/wall thickness. So you'd enjoy the full range of factory hunting ammunition of course. The .30 RAR was limited by lug length and extension tooth length.

For a hunt or TGT shooting, you could push it a little more with hand loads, so a 12.5" Anvil Grendel could do about 2489fps with a 123gr SST, which is 18" velocity. At sea level, that would give you a 400yd expansion range.

400yds 1804fps 888 ft-lbs

A normal 12.5" Grendel with the factory 123gr SST load at 2350fps gives you 75yds less expansion range:
325yds 1803fps 888 ft-lbs

I think for most hunters, they aren't going to care so much about reaching far beyond 200yds with an SBR, and the way I look at it personally is that I want as light of a little pistol/SBR as possible.

Now for TGT shooters or longer range hunters, let's look at some numbers. With a 20" Anvil Grendel, you could get a 123gr to 2715fps at 56ksi with CFE223, but a 20" AR15 Grendel can get 2653fps at 50ksi with CFE223 under a 123gr.

I'd have to see what the lug length is on the Anvil and it it's similar to the 30 RAR bolt. The mechanical engineering limitation is bolt telescoping length into and out of the extension, as well as travel length of the carrier and extended bolt to get past the bolt catch. You also have bolt mass that has to be rotated by the inertia of the carrier before it can be withdrawn from the extension. Since they have more room with the Anvil receiver set, they might have increased the lug lengths to AR10 dims.

You can see the difference in lug length here between the 30 RAR BCG (Middle) and AR10 BCG (Far).


If that's the case, then it will have more pressure tolerance than the 30 RAR bolt and extension, which were constrained to the AR15 length action, even though Remington used a larger diameter barrel extension and tunnel for it in the upper receiver.

You start to see why DPMS and Remington just decided to go with a smaller AR10 action with the larger, popular .308 case and magazines, rather than trying to tweak into an AR15. That 30 RAR AR15 is a nice hunting set-up though because it is still very lightweight, while packing a lot of charge weight into a short, fat case with similar case length to a Grendel, while feeding from a single ramp presentation magazine and barrel extension. I just wish they would have done it in 7mm or 6.5mm versus .30 cal.