Short Barrel 6.5 Creedmoor vs Short Barrel 6.5 Grendel

[LRRPF52]

Cool video comparing velocities between Grendel and Creedmoor.

[Okie_Poke]

Interesting. Grendel with 123s was ~2315 and Creedmoor with 120s was about ~2425. I couldn't tell, maybe because of my lack of attention span, whether he was using equal length barrels for both of those or not. I caught the Creedmoor was 11.5 inches but didn't catch whether the Grendel was the same length.

[LRRPF52]

The crazy thing is that my 12” Grendel shooting 120gr Federal OTM box ammo averaged 2393fps from an 11rd string.

Keep in mind Grendel is operating at 47,000-51,000ksi from factory ammo, and 6.5CM is operating at 58,000-61,500psi in factory ammo, with 41-44gr of slower-burning powder.

His barrel lengths appear to be within ~1” of each other, either way.

I’ve been into the large frame AR-10s for decades now, having owned a lot of them, worked on, troubleshot, rebuilt, repaired, and had many come through courses. I think the 7mm cartridges make more sense if you want to get the performance out of it compared to 6.5mms in the large frame, namely 7mm-08, 7mm SAW, and 7mm SWC. Velocities won’t be that high with the really high BC bullets, but you get BC advantage over lighter stuff when shooting 162-180gr 7mms. They hit steel really hard too, very minimal wind drift.

What I like about 6.5 Grendel is being able to watch my rounds fly into the steel without my sight picture moving much at all. Self-spotting is very easy, even with the 12” Grendel. Much easier than with my 22” heavy-barreled .260 Rem AR-10, for example.

[A5Blaster Number 2]

The crazy thing is that my 12” Grendel shooting 120gr Federal OTM box ammo averaged 2393fps from an 11rd string.

Keep in mind Grendel is operating at 47,000-51,000ksi from factory ammo, and 6.5CM is operating at 58,000-61,500psi in factory ammo, with 41-44gr of slower-burning powder.

His barrel lengths appear to be within ~1” of each other, either way.

I’ve been into the large frame AR-10s for decades now, having owned a lot of them, worked on, troubleshot, rebuilt, repaired, and had many come through courses. I think the 7mm cartridges make more sense if you want to get the performance out of it compared to 6.5mms in the large frame, namely 7mm-08, 7mm SAW, and 7mm SWC. Velocities won’t be that high with the really high BC bullets, but you get BC advantage over lighter stuff when shooting 162-180gr 7mms. They hit steel really hard too, very minimal wind drift.

What I like about 6.5 Grendel is being able to watch my rounds fly into the steel without my sight picture moving much at all. Self-spotting is very easy, even with the 12” Grendel. Much easier than with my 22” heavy-barreled .260 Rem AR-10, for example.

I still remember the first time my best friends brother shot my 16 inch grendel at 900 yards.

He is a retired LC USMC, he looked at me and said he had never before ever seen a bullet travel down range and impact.

The look on his face was priceless.

Tried to buy the gun off me right then and there.

[LRRPF52]

I felt cheated, having humped a beast of an M24 SWS with its internal 5rd magazine. I never was able to spot my own hits that well with it, and it weighed 14lbs. That was back in the day when there was nothing on them other than the Leupold M3A and an old non-swivel Harris bipod.

Ft. AP Hill, Summer 1995 Recon Platoon training:


Camp Greaves, Republic of Korea, Summer 1996 (notice how huge the muzzle OD is on the M24):

I feel just as confident in my hit probability with a lightweight Grendel, because I can see what’s happening. You can do everything a Rifleman needs to do as well, with better terminal performance than any M16 or M4.

[lazyengineer]

A little bit cherry-picky.

First off he used an AR10 rather than an SFAR; which yea - is going to recoil and suck. Any 6.5CM class AR that isn't an SFAR or POF, is obsolete. (I'm opinionated). In my experience, my 20" SFAR in 6.5CM recoils notably less than my AR10 6.5CM did, I guess due to the huge BCG. The part that confuses me is my 20" 6.5CM SFAR, which is lighter than my 20" 6.5 Grendel - actually recoils less than my 20" 6.5 Grendel. I don't have an explanation, other than it just does for me.

Second, that BBL length is getting short. So sure, at 11" BBL, the differences will get slighter. 11" is prettttyyy short.

Third, he ran 120's, undermining the 6.5 advantage of running the heavy bullets. That's the most cherry-picked part of the test.

Now compare 14.5" and run 140's in the 6.5CM. Hint - that 6.5CM it's still supersonic at 1000 yards out of a 14.5", and it's ft-lb impact is still over 1000 out to like, 500 yards.

But yes, I still have and run my 12" 6.5Grendel, and it's a great little gun with a lot of umph for it's size. Downright remarkable in fact. But to suggest than a short 6.5Grendel is on part with a short 6.5CM, takes a pretty darned short barrel comparison and some cherry picked ammo, to actually validate that. If the gun-market wasn't in the toilet, and I could actually get my money back, I'd sell my 20" 6.5 Grendel in a heartbeat.

[A5Blaster Number 2]

A little bit cherry-picky.

First off he used an AR10 rather than an SFAR; which yea - is going to recoil and suck. Any 6.5CM class AR that isn't an SFAR or POF, is obsolete. (I'm opinionated). In my experience, my 20" SFAR in 6.5CM recoils notably less than my AR10 6.5CM did, I guess due to the huge BCG. The part that confuses me is my 20" 6.5CM SFAR, which is lighter than my 20" 6.5 Grendel - actually recoils less than my 20" 6.5 Grendel. I don't have an explanation, other than it just does for me.

Second, that BBL length is getting short. So sure, at 11" BBL, the differences will get slighter. 11" is prettttyyy short.

Third, he ran 120's, undermining the 6.5 advantage of running the heavy bullets. That's the most cherry-picked part of the test.

Now compare 14.5" and run 140's in the 6.5CM. Hint - that 6.5CM it's still supersonic at 1000 yards out of a 14.5", and it's ft-lb impact is still over 1000 out to like, 500 yards.

But yes, I still have and run my 12" 6.5Grendel, and it's a great little gun with a lot of umph for it's size. Downright remarkable in fact. But to suggest than a short 6.5Grendel is on part with a short 6.5CM, takes a pretty darned short barrel comparison and some cherry picked ammo, to actually validate that. If the gun-market wasn't in the toilet, and I could actually get my money back, I'd sell my 20" 6.5 Grendel in a heartbeat.

Looks to me the guy used what he had or could afford.

You can always spend your cash too rework the test under your ideal conditions and report back the results.

Do I have a creedmoor? Yep. Is it superior to grendel with heavier bullets and long barrels? Yep.

Is enjoyable to carry around afield? Nope.

Just saying.

[LRRPF52]

A little bit cherry-picky.

First off he used an AR10 rather than an SFAR; which yea - is going to recoil and suck. Any 6.5CM class AR that isn't an SFAR or POF, is obsolete. (I'm opinionated). In my experience, my 20" SFAR in 6.5CM recoils notably less than my AR10 6.5CM did, I guess due to the huge BCG. The part that confuses me is my 20" 6.5CM SFAR, which is lighter than my 20" 6.5 Grendel - actually recoils less than my 20" 6.5 Grendel. I don't have an explanation, other than it just does for me.

Second, that BBL length is getting short. So sure, at 11" BBL, the differences will get slighter. 11" is prettttyyy short.

Third, he ran 120's, undermining the 6.5 advantage of running the heavy bullets. That's the most cherry-picked part of the test.

Now compare 14.5" and run 140's in the 6.5CM. Hint - that 6.5CM it's still supersonic at 1000 yards out of a 14.5", and it's ft-lb impact is still over 1000 out to like, 500 yards.

But yes, I still have and run my 12" 6.5Grendel, and it's a great little gun with a lot of umph for it's size. Downright remarkable in fact. But to suggest than a short 6.5Grendel is on part with a short 6.5CM, takes a pretty darned short barrel comparison and some cherry picked ammo, to actually validate that. If the gun-market wasn't in the toilet, and I could actually get my money back, I'd sell my 20" 6.5 Grendel in a heartbeat.

Cherry-picking would have been if he only ran 140s in the 6.5CM vs 120s in the Grendel. He ran 123gr in Grendel and 120gr and 147gr in 6.5CM, with no downrange ballistics comparison, just looking at muzzle velocities.

For recoil comparison, both shooters said they couldn’t really tell much difference between the two, so I think this is a combination of the AR-10 weighing more to compensate for its additional propellant mass and reciprocating BCG effects. Both weapons had what appears to be the same type of muzzle brake.

Your 20” SFAR, if stock from the factory, has adjustable gas so it can be dialed down to be tamed well.

If you use the same adjustable gas on the same weight rifles, same gas system lengths, same BCG weight, the Grendel will recoil less than 6.5CM.

I’ve been shooting .260 Rem, 6.5x284, 6.4x47 Lapua, and 6.5CM AR-10s since the 2000s, have owned 2x .260 Rem AR-10s, and my sight picture at the break of the shot with the 6.5-08 class of rifles is nothing like it is with 6.5 Grendels. With Grendel, even the little 12”, I just watch my round go in. With 6.5-08 14lb rifles, the bullet connects or misses before I can recover my sight picture. Maybe I need to dial-in the large frames more with adjustable gas. Bootleg makes a large frame Adjustable Gas Carrier now.

RifleSpeed is one of the best options for the -08 class of ARs as well. I have a Savage MSR-10 with adjustable gas I haven’t even messed with, as it’s in .308 Win. That frame size is about ideal for the .308/6.5CM class. I’m thinking of chambering it in one of the 7mms though.

[biodsl]

A few years back, I bought a 16" heavy barrel Remington 783 in 6.5 Creed. It was very cheap and I thought it would be fun to see what kind of precision I could get out of it. It shot factory Hornady 120 ELDM @ 2522 fps. My 16" AR in Grendel shot factory American Gunner 124gr @ 2415. I sold the Creedmoor.

[StoneHendge]

A little bit cherry-picky.

Any 6.5CM class AR that isn't an SFAR or POF, is obsolete.

I'm still waiting to see someone (anyone) use a SFAR or POF for PRS gas gun or practical long range AR matches, especially given both Ruger and POFs history of sponsoring. Especially POF since they are in Phoenix and are a huge sponsor in the area (where I am). I'm guessing its either accuracy or functionality under fast strings of fire. If anyone does know of anyone who has successfully used one, I'd love to see the results.

[imaguy3]

I'm in southern arizona, POS fail a lot (nickname we gave POF).. In my rifle instructor course and a full auto instructor course, the guys with POF rifles were non stop failures.

My buddy has a ruger sfar and we use it for hunting. He has zero issues with his gun and he got it when it was first released.

[LRRPF52]

I just ran the 120gr ELD-M 6.5 Creedmoor load through Shooter’s Notes velocity estimator, which has been within 11fps of real-world muzzle velocities for me every time I compare it.

Hornady stated 24” MV for the 120gr ELD-M is 2910fps. When entered into the calculator and barrel length changed to 11.5”, it gives me:

11.5” 6.5CM 120gr ELD-M
2458fps

11.5” 6.5CM 147gr ELD-M
2277fps

So for the 120gr ELD-M, that’s more like 16-18” Grendel velocity with a 120gr. For the 147gr ELD-M, that’s akin to 24” Grendel speeds with 140-147gr.

[StoneHendge]

I just ran the 120gr ELD-M 6.5 Creedmoor load through Shooter’s Notes velocity estimator, which has been within 11fps of real-world muzzle velocities for me every time I compare it.

Hornady stated 24” MV for the 120gr ELD-M is 2910fps. When entered into the calculator and barrel length changed to 11.5”, it gives me:

11.5” 6.5CM 120gr ELD-M
2458fps

11.5” 6.5CM 147gr ELD-M
2277fps

So for the 120gr ELD-M, that’s more like 16-18” Grendel velocity with a 120gr. For the 147gr ELD-M, that’s akin to 24” Grendel speeds with 140-147gr.

Just shy of 2900 is where I've topped out with a 123 Scenar in a 22" CM using H4350. I'd imagine the burn speed makes it inefficient in a short barrel. I wonder how Varget would perform. It gives accuracy in CM but runs quite a bit slower out of longer barrels. I wonder if it would be more efficient in a short barrel

[LRRPF52]

Another thing that gets overlooked, has been tested and duplicated, is the effect of recoil in lighter guns vs muzzle velocity.

Cartridges with more propellant mass generate more recoil, so if the gun is lighter, it will travel to the rear more as the projectile is moving down the barrel, effectively “limp-wristing” the gun and generating less measured muzzle velocity.

A pistol or mini carbine version of an AR-10 would be a prime set-up that suffers from this phenomenon.

This could explain why there aren’t significant muzzle velocity differences with the 120gr projectile weight, even though 6.5CM is spitting it out using 44gr of powder and 62,000psi, whereas 6.5 Grendel is only using 28gr and ~49,000psi with factory ammo, with around half the recoil energy.