Barrel length in 6.5 Grendel

[Buck13]

About how much velocity difference will a 20" vs 24" barrel make in 6.5 Grendel? Load data and a few available uppers have 24" but 20" are more commonly available. Interested in hunting, so benchrest accuracy isn't the goal, unless barrel whip gets REALLY bad with 24".

 

[horsemen61]

I’d get the 20 inch personally and you can figure about 25 fps per inch of loss I have an 18 inch and I love mine

 

[Buck13]

I’d get the 20 inch personally and you can figure about 25 fps per inch of loss I have an 18 inch and I love mine

A 20" from Bear Creek is so much less expensive than anything else I see right now that it's pretty hard to quibble over 100 fps. $300 with a fluted barrel sounds good, if they work halfway decently.

 

[westernrover]

24" is going to have the best ballistics and gives the Grendel the range needed for hunting effectively between 200 and 300 yards. How much the 20" barrel reduces the effectiveness is going to depend on the particular bullet and load used and possibly the type of action. I will just say that when pushed to maximum performance in a 24" barrel bolt-action rifle, the Grendel is something I would hunt mule deer with and have confidence out to 275 or 300 yards. Within that range, I don't think the deer could tell the difference between Grendel and Creedmoor. I would expect a 20" barrel to reduce that by at least 50 yards. The issue is with velocity, bullet design, and expansion.

MPBR is another issue. If you use a laser rangefinder and dial, then it's no issue. If you use a 200 yard zero, the 24" barrel will give you at least 25 more yards of MPBR versus a 20" barrel.

My 24" is on a mini bolt-action receiver. I can totally see why the 20" would be more appealing for an AR receiver. If you hunt deer in the tight woods, there would be no practical disadvantage to the 20". Also, hunting hogs at close range, no difference. Stretch the shots out over the long range for mule deer and pronghorn, then a 20" AR-15 is not the best tool.

 

[rdnktrkr]

I have a 20 and 24" AR and a friend has a 18", at a recent shoot we were at it was easier to ring steel with my 24 than his 18, he has since changed his barrel out to 22" (I think) and he said he likes it better. At the CMP Talladega I can stay on target easier with my 24 but that might be because I've had it longer and know how it shoots. All I've used mine for is at the range but I purposely bought the 20 for a hunting rifle

 

[brewer12345]

I used a 20" to kill a large doe at 325 yards last month. I used a 123 grain SST hand load that chrono'd at 2400 FPS, a good 125 FPS less than a Hornady Black factory offering. One hit to the chest and she went down like a ton of bricks. I will do some more load workups to see if I can get more speed for this Fall, but I would say that 18 or 20" would be fine to 350 yards, maybe more.

 

[Varminterror]

The influence of ~80-100fps difference between a 20” and a 24” on hunting efficacy is much less significant than the influence of the weight of 4” of extra barrel on the balance of the rifle.

I can say, from experience, none of the speculation above about deer at only 275-300yards or comparison to the Creedmoor is at all consistent with what I’ve seen. We can do more with the Creed case than the Grendel, and deer will die quickly by the work of the Grendel at distances far longer than 275-300.

The last 6.5 Grendel I built for myself was ~4 years ago, and was a 20”, meant for more diverse use. My most recent Grendel has been a 6 Grendel wildcat, the 243 LBC, which I built at 24” (and would have preferred 26”) to get as much forward balance as I could get via barrel length rather than forend weights. Horses for courses.

20” 6.5 Grendel

24” 6 Grendel

 

[CraigC]

I would choose barrel length according to weight and balance, not velocity. I did an 18" before and wasn't happy with the weight, so built a lightweight 16" last summer.

 

[GooseGestapo]

The velocity loss 24”-20” is more on the order of 50-75fps.
The short, fat small capacity case is VERY efficient!
This mitigates much of the velocity loss due to shorter barrels.
I’ve got a BCA 20” spiral fluted barrel upper.
It’s adequately accurate but decidedly on the heavy side!
I want a bolt action rifle for hunting/stalking. I keep bouncing between the 16-1/2” and 22” Ruger American.

 

[adcoch1]

For general use my 6.5 Grendel ar is a 16". And that's a patrol rifle build. If I want to maximize the cartridge I grab my Ruger American predator with a 22" barrel. Lot more scope on that rifle, since future antelope hunting was the intended purpose when I bought it. A 24" AR-15 is kinda cumbersome...