Question for 6.5 Grendel AR owners/ordering a barrel

[Ray P]

On Monday, I plan to order a custom 6.5 Grendel (SAAMI) stainless barrel for an AR15; 24-inch length, 1:8 twist, 5R rifling, SPR or HBAR, with a fitted bolt. But I'm not certain this is an optimum combination.

From your experience, what options (length, twist, cryo, etc) would you order for a new 6.5 Grendel barrel intended for an AR? My primary use will probably be paper punching, but I don't want it to be too heavy for pursuit of deer or antelope

I'm going with 6.5 Grendel for the flat shooting characteristics of a 6.5, the higher bullet mass over a .224, a reputation of being a good performer at 300+ yards, and the benefits of a smaller action over an AR10.

Going to be putting it on a really nice set of 17Design billet upper & lower receivers, with RRA 2-stage trigger and SI lower parts. (edited to fix typo)

 

[funnelcake]

IMO 24” is too long and many are some kind of heavy profile so carrying it gets old fast. A good compromise is 18-20” medium profile. You don’t really need 1:8 twist in 20” and longer barrels with the 6.5G.

I don’t have a Grendel barrel longer than 16” at this point.

 

[someguy2800]

I detest long heavy barrels on an AR. The longest I would buy would be lightweight or fluted 20” and I really prefer 16 or 18”.

 

[gotboostvr]

Agree, a 24" Hbar will be heavy to carry afield.

A 16" Hbar will still have enough barrel length to get out there pretty good and not be as heavy.

I'd personally pick a medium/spr/dmr/whatever you wanna call it profile of either 16-18" for a double duty rifle.

 

[CraigC]

I agree with the others that 24" is too long. I did one last year with an 18" Grendel Hunter upper and it was a bit on the chunky side. I just put together another with the 16" Faxon barrel and it is just right but this is purely as a hunting rifle. Of course it helps to use a 1" optic over a 30mm and a CTR buttstock over the UBR. For most target use, you might like the 18".

 

[mrcabinet]

24" is unnecessary. My 20" shoots 1" groups at 200 yd.s all day, which is more than adequate for my needs. And that's with an inexpensive BCA barrel.

 

[troy fairweather]

I'd go 18-20"

 

[funnelcake]

This would be a good compromise but still over 30-oz (32.1): https://shopwilsoncombat.com/BARREL...S-GLASS-BEAD-1-8/productinfo/TR-65GRCRG18FT8/

Faxon makes 18 and 20-inch "Gunner" profile barrels that are very light...just difficult to find in stock these days.

 

[horsemen61]

IMO 24” is too long and many are some kind of heavy profile so carrying it gets old fast. A good compromise is 18-20” medium profile. You don’t really need 1:8 twist in 20” and longer barrels with the 6.5G.

I don’t have a Grendel barrel longer than 16” at this point.

Why do you feel this way the reason I ask is because I think the 1~8 twist is fine in my experience I have 3 grendels at this point in time and they are all 1~8 I’ve never had a 1~9 and I think I may need to fix that…..

 

[funnelcake]

The longer the barrel is, the more time the bullet spends exiting. Even the long stuff like 129-gr. will apparently stabilize just fine out of 20-24 inch tubes w/ 1:9. IIRC, Alexander Arms (started by the guy that designed the cartridge) still uses 1:9 in their longer barrels. I don't think 1:8 would hurt in those unless you're shooting really light hence short bullets.

 

[horsemen61]

IMO 24” is too long and many are some kind of heavy profile so carrying it gets old fast. A good compromise is 18-20” medium profile. You don’t really need 1:8 twist in 20” and longer barrels with the 6.5G.

I don’t have a Grendel barrel longer than 16” at this point.

Why do you feel this way the reason I ask is because I think the 1~8 twist is fine in my experience I have 3 grendels at this point in time

 

[BigBlue 94]

I have 2 Grendels. A 20" M16A1 insipired build and a 24" paper puncher.

The 24" is a stainless HBar model, chambered in 264 LBC from Satern iirc. I dont recall if its 1-9 or 1-8. The 20" is 1-8 twist.

The 24" barrel is Loooooong

 

[Legionnaire]

I recently purchased a 20-inch PSA upper in 6.5 Grendel. I don't think it's too long. When I build a 6mm ARC it will be a 24-inch.

 

[greyling22]

I'd echo the 18-20" crowd. Unless you're going suppressed. Then 16".

I have a ballistic advantage hanson Barrel. Shoots ok. I might do a Wilson if I was doing it again. I've been very impressed with my hamr barrel from Wilson.

I've been shooting the 123sst. When they're gone I'm going to switch to the 90grn tnt.

 

[Double Naught Spy]

I like heavy barrels. Long doesn't bother me, either, although most of my hunting is with 18" or 20" heavy barrels. The only bad thing about the length, as far as I am concerned, it that longer guns are a bit more difficult to handle, particularly when suppressed. You can get MOA accuracy out of a 7" barrel or a 24" barrel. You can also get 4 MOA out of either. I understand some people will go cheap and often get lucky with a very good barrel. I have mostly gone the other way with higher end barrels and never been disappointed with accuracy.

If you are worried about weight, get a good sling, wider. Yes, all the weight of your gear adds up. That is true. If you have a carrying capacity limit, then going with a longer barrel may mean a 1.2 pounds of weight (going from 18" to 24") means you must remove 1.2 pounds elsewhere in your kit. The benefit is some additional velocity which may not matter on shorter shots, but may matter on longer distances shots, particularly relative to how well your bullet performs (i.e., expansion). Is the extra 100-150 fps important to you?

 

[rbernie]

Full disclosure: I do not own a 6.5 Grendel, but that does not stop me from having an opinion.

It seems to me that the whole point of the 6.5 Grendel is downrange performance past 300 or 400 yards. I’d have to believe that velocity, therefore, is reasonably important.

 

[redneck2]

It seems to me that the whole point of the 6.5 Grendel is downrange performance past 300 or 400 yards. I’d have to believe that velocity, therefore, is reasonably important.

That’s a great point. Assuming the old rule of 50 FPS per inch of barrel, you’d be talking 400 FPS difference between a 16 vs 24. I have zero idea if that’s factual. Even 30 FPS per inch would gain about 10%.

Were I to scratch build another AR, it would most likely be a 6.5 with a high end 24” light barrel. I’ve got a 24” pencil barrel on a Varminter and it’s fine

 

[rbernie]

Looks like Carbon6 will make you a 24" 6.5 Grendel threaded barrel with any twist rate you want between 1:7"-1:10" for less than eight bills.

https://carbonsixllc.com/product/carbonsix-ar-style-barrel/

 

[mavracer]

It seems to me that the whole point of the 6.5 Grendel is downrange performance past 300 or 400 yards. I’d have to believe that velocity, therefore, is reasonably important.

That’s a great point. Assuming the old rule of 50 FPS per inch of barrel, you’d be talking 400 FPS difference between a 16 vs 24. I have zero idea if that’s factual. Even 30 FPS per inch would gain about 10%.

The smaller the case and longer you go with the barrel the less of a percentage increase you'll see.
My gut tells me your 10% might even be a smidge high.
A 10% increase is going to have a fairly linear 10% decrease in drop and increase in range.
A 16-18" Grendel will still shoot well past 400 and be much more portable.

with RRA 2-stage trigger

Do you already have the trigger? I have both and I like the Larue MBT better, not enough better that I've replaced the RRA though.

 

[cfullgraf]

I have several AR-15s with 24” barrels and one with a 26” barrel. All are either 17 Rem, 204 Ruger, or 223 Rem and they tip the scales at 11 to 12 pounds.

A 6,5 Grendel would be a bit lighter due to the larger bore and maybe a slimmer profile than my heavy varmint barrels but it would still be heavy.

If no muzzle device, I’d get a 20”’ barrel. 18” if using a muzzle device.

 

[Varminterror]

For most users seeking a “general purpose Grendel,” a 20” rifle, 1:8” twist in a NM/DCM contour is ideal. Long enough to promote great speeds, but not overlength, heavy enough to promote great stability, but not overweight.

The speed advantage per length for the little Grendel case is smaller than larger cases with higher expansion ratios. The Grendel only picks up around 20fps/inch in the length-range we’re discussing (Berger states 17fps/inch). IF YOU ARE REGULARLY SHOOTING PAST 1000 YARDS, GET 24”+, otherwise, 20” does everything you’d want and need. The 24” bull and semi-bull barrels (.875” and .936” journals) have their place, but most guys aren’t doing that kind of specialized shooting, so they don’t need that kind of specialized rifle.

Here’s one of my favorite Grendels I have ever built. This one could hold onto 1MOA past 900, and I used this one in competition as far as 1200. 20” 1:8” twist, NM contour (heavy under the guard, 0.75” journal). This was one of my favorite AR’s I have ever built, or have even handled. I might not choose that Vortex Viper HSLR again, but I’ve thought frequently about building another Grendel just like this. Really, really hard to beat this AR for versatility and capability.



Admittedly, I find more use for the 6 ARC than the 6.5 Grendel - I just put together another 243 LBC (6 Grendel) for my son this winter, 24” Semi-bull, 1:8”. It’s heavy, but it’s made for reaching a long, long ways with a small frame AR. It’ll hunt deer just fine as far out as I would want or need, and is lighter and shorter than most of the rifles I’ve used for hunting in recent years. But I find the little Grendel case to be about perfect to get the most performance from the small frame AR as possible; short enough case to still fit long ogive, high BC bullets into AR mag length, but enough case diameter to still fit enough powder to push them to sufficient speed to actually get some work done.

 

[Ray P]

wow.

Got sucked in by taxes today, and I'm only now getting the chance to check this thread. There is great info in the comments, and I'm not sure I'm processing it all. I will need some sleep before I can put together coherent responses to so many great comments and questions.

But thank you all. More in a few hours

 

[rdnktrkr]

while shooting steel recently with a friend it seemed my 24"BCA fluted stainless was out performing his 18"BCA 6.5 Grendels, there is nothing special about mine, I've polished the trigger, installed different springs and installed setscrew for trigger reset, he has a drop in trigger I think is a RRA and some special stock. If for range work only I think the 24" works great, I also have a couple of 20" ARs one is a colt from the early 70s and the other is a new build, they both shoot better than my 16" home defense guns but the 20" build has a better scope, trigger and stock.
If I was building a new AR today I would look closely at the 6mmARC, it is basically a 6.5 Grendel necked down to 6mm, same bolt and mags, I think for paper punching it would be hard to beat

 

[JCSC]

I shoot a 20” Odin DMR for hunting. It’s a heavy little gun, but I don’t think you could find a better SC deer rifle.

24” I wouldn’t want to drag around.

stay away from BCA u less that’s all the budget allows.

 

[jmorris]

Mine is 24”, I am used to shooting 20” barrels with suppressors. A naked 24” is lighter and shorter than a 20” with a can on it.



I would much rather carry the 24” AR 15 than a 16” AR 10. That said, I don’t haul them around a lot, hunting in tight places, as I have built rifles just for that purpose.

It’s your rifle, get what you want. When one says, 24” is too long but 16” is too short, you have to ask, for what? For them, is the answer.