24" Barrel lightweight AR build?

[Squirrelmarm]

I'm trying to build an AR-15 in 6.5G that is lightweight (~7lbs with scope) that I would like to hunt with. I currently have one with an 18" barrel and it's kind of heavy at 9lbs with the scope. I would like to have a 24" barrel, but every one available that long is some heavy profile (bull barrel, HBAR, etc.). For this build if I can just get to 1moa accuracy I will be happy. There are a few custom barrel makers like McGowan and Columbia River Arms that can make what I want.

I was just curious if anyone else had experience building an AR-15 with a longer lightweight barrel? Did you get good cold bore accuracy or have other issues?

I know some of you will want to tell me I should just get a shorter barrel, which is fine, but I am curious if anyone has experience with rifle-length lightweight barrels in 6.5G. If anyone knows of a suitable 20"+ barrel I'm all ears. Thanks.

[myrifle]

With that long of a barrel. You will never get it to your target weight with scope.

That's just to much steel to make that weight.

Not to mention its going to be extremely whippy on the shot do to its length and how thin it would have to be too even come close too making your stated weight goals.

[VASCAR2]

The only 24” 6.5 Grendel I’ve seen in the last couple years have been the Cz 527 American bolt action with a 24” barrel. I’ve never weighed mine but with a light scope you might meet your weight requirement. Lilja, Precision Firearms would probably build you whatever barrel you want. Odin Works has sold light weight barrel but I don’t remember any that were 24” long.

Several years ago AA sold a 24” CMV barrel in 1:9 twist which was not a bull barrel. A Friend has one and my son in law has a 22” Lothar Walther 6.5 Grendel but it is not a light weight barrel. Satern/Liberty made a lot of 24” 6.5 Grendel barrels sold by Brownell’s and Midway. I don’t remember any of them being a light weight profile. Criterion sell a 22” bull barrel 6.5 Grendel in stainless steel. You could always get a heavy SS barrel turned down to make it lighter.

For a hunting gun I suggest you look at the velocity difference between 20”-22” & 24” barrels. Once you get longer than 20” the velocity gain decreases as the barrel gets longer. There is a forum member mel who has a 28” 6.5 Grendel AR-15 that has posted quite a bit about his build.

I think you’ll have to find a barrel to turn down to the contour you desire or get a custom made barrel.

[grayfox]

You don't give much info about what and why for the hunting, what will you be hunting for, and why the need for so light?
What types of game and what distances...
or do you just have a "thing" for 24" light weight ARs?
"Light" suggests walking about but 24" suggests some "need" for long distance shots... hence accuracy becomes an issue.

There's a reason most longer barrels are heavier profiles.

Personally, I doubt if you will find your dream 24" lightweight, accurate AR style grendel.

9 lbs isn't that heavy for many guys (for me if I was doing a lot of hiking, yes 9lb is not my ideal), I have some that tip at 10 lbs but I don't fancy doing a lot of hiking with them.

If you need barrel length then a CZ is probably your best bet, course it's not an AR. 24-25" from what I read.
Howa has a standard 22" barrel as well.

Then there's that 14 yr old girl who killed her bull elk at 392 yds (U tube vid), with a 22" AR grendel. Took 3 shots (3 hits) though but she did it.

[Old Bob]

Wilson Combat has this barrel at 52oz...

https://shopwilsoncombat.com/BARREL-65-G...SSRG22FT8/

And this one at 39.6oz. This is the barrel I have on my 6.5 Grendel AR.

https://shopwilsoncombat.com/BARREL-65-G...RCRG20FT8/

[StoneHendge]

I have a 16" 6 ARC that weighs in ~7 lbs with a 17 oz scope. It has a mix of high-end lightweight parts and the Lilja barrel is pretty much a straight 0.75" contour and weighs in around 27 oz. What you are looking for is unachievable. Any longer barrel would need to be so thin that there would be excessive whip and you'd get nowhere near your accuracy goal.

I don't know how long Proof Research goes in Grendel these days, but one of their carbon fiber barrels would probably get you closest to your goals. But if your going to spend that kind of cash and a high velocity 6.5mm bullet in a lightweight package is your goal, you should at least look at the POF Prescott - a 7lb 6.5 Creedmore in an AR-15 sized package.

[Squirrelmarm]

... Satern/Liberty made a lot of 24” 6.5 Grendel barrels sold by Brownell’s and Midway. I don’t remember any of them being a light weight profile. ...
I think you’ll have to find a barrel to turn down to the contour you desire or get a custom made barrel.

Yes, the Brownell's 24" barrel is the closest commercially available barrel to what I am thinking of. It weighs just over 2.5lbs. I have the 18" version and it shoots just over 1moa with factory ammo. I haven't found a hand load that it likes yet, though.

I think you are right that I will need to go with a custom build for my picky tastes.

I have a Tikka T3x Superlite that has a lightweight fluted barrel but still shoots under 1moa with factory ammo. So I know some high quality lightweight barrels are capable of great accuracy. That's why I'm asking. Right now I'm just kind of shopping around and getting ideas.

[Squirrelmarm]

What you are looking for is unachievable.

Challenge accepted.

[StoneHendge]

Challenge accepted.

We'll need to see video shot from behind you to verify accuracy - not just holes in a target.

Feel free to use this as a resource on a lightweight build. https://www.65grendel.com/forum/showthre...ightweight

[Squirrelmarm]

We'll need to see video shot from behind you to verify accuracy - not just holes in a target.

Feel free to use this as a resource on a lightweight build. https://www.65grendel.com/forum/showthre...ightweight

Thanks for that link. Faxon makes a 20" barrel that they claim is 1.98lbs. I may go with that if I can't find something more suitable, if they will make it again.

[grayfox]

I have a Tikka T3x Superlite that has a lightweight fluted barrel but still shoots under 1moa with factory ammo. So I know some high quality lightweight barrels are capable of great accuracy. That's why I'm asking. Right now I'm just kind of shopping around and getting ideas.

A bolt gun, with accuracy from factory loads.
AR's are of course different animals.
As to accuracy, your trouble in finding an accurate load that your current barrel likes is testimony to rack-grade performance, which is a roll of the dice.
Anything other than lilja, bartlein, krieger etc top-end barrels will simply be another roll of same dice. Just sayin'.

[tdbru]

Squirrelmarm,
i too was after a light weight AR with as long a barrel as i could in 6.5 Gr.

my first AR upper was a heavy barrel BCA 24" 6.5 GR. which was what i thought i wanted. it shoots ok for a rack grade barrel. get good velocity out of it. but the rifle ended up quite heavy.

so i tried to build a light weight 6.5 Gr. upper. i wanted the experience of building my own upper, and i wanted something light and long barreled. I too, could find no light profile 24" barrels available. the longest i could find, excluding calling brux or other barrel makers and gunsmiths and having them make one, was the 20" Faxon Gunner. So that is what i used.

if i recall, i think the rifle & scope weight with the light upper on it came in ~8.25 lbs. much better than the 24" bull barrel BCA upper, as expected, but still not "light weight".

if you really want the weight of my Gr with the light upper on it, i can go get it out and weight it and give you a more accurate answer.

with sierra 85gr. HP and benchmark i came up with a load that would shoot 1 MOA and occasionally a bit better. Other bullets tended to get bigger groups, but nothing came in over 2.5 MOA.

a better shooter than i could probably do much better.

i remember a long time ago, when COLT was the only one making a civi AR and it was the SP1. i picked one up. of course no scope, but i don't think it weighed more than 6.5 lbs. was quite light.

years later i picked up a CMP match AR. they'd put lead in the butt and barrel handguards and had a bull barrel on the thing. if i recall it was around 18lbs. or so.

anyway, i could only get down to 8 1/4 lbs without a custom barrel, and that was on a 20" production tube.

I am not sure about VASCAR2's comment that speed decreases after 20". If i recall Mel's postings, his 28" tube got great velocity. perhaps what VASCAR2 's comment meant was after 20" the rate of velocity increase starts to diminish. My 24" HB does shoot bullets faster than my 20" light upper. to be precise i'd have to look it up, but if i recall it was in the 50 to 75 fps range depending upon bullet. i.e. speed did favor the 24" tube for me, but the gain over the 20" wasn't astonishing.

best of luck on your new upper build.
-tdbru

[Mesa1978]

I have one of the 24" Midway versions of the stainless Brownell/Liberty offering. It is old and has 5R rifling. I got lucky and managed to get one without the short chamber. It is much lighter than an AA Overwatch and is about a 1 MOA shooter mounted to a Vltor upper and Les Baer carrier with handloads. My daughter loves to shoot it.

[Squirrelmarm]

... to be precise i'd have to look it up, but if i recall it was in the 50 to 75 fps range depending upon bullet. i.e. speed did favor the 24" tube for me, but the gain over the 20" wasn't astonishing.

Thanks for your comment, if the velocity gains are so minimal I might go with a 20" barrel after all. Weight savings is more important to me. My current build is 9lbs with an 18" barrel, I think it's too heavy. Like I said I'm more just scoping things out at this point, I will probably start on this build sometime next year.

[VASCAR2]

Here is some chronograph data I got using a Magnetospeed a few years ago and tdbru is correct. The velocity gain per inch decreases more past 20”. The shorter the barrel the more FPS are lost per inch but with longer barrels once you get passed 20” the gain in velocity is less per inch. There is also a graph illustrating the velocity for given barrel length.

Here is a list of the tested ammo by average velocity for each barrel length.

120 Grain HP BT PPU

16" 2392

18" 2455

20" 2480

24" 2559

110 grain FMJ PPU

16" 2510

18" 2570

20" 2614

24" 2683

123 grain A-Max Hornady

12” 2265 (123 grain ELD-M)

16" 2419

18" 2464

20" 2505

24" 2568

123 Grain SST Hornady

12” 2277

16" 2430

18" 2493

20" 2511

24" 2583

Hand Load 123 Grain Nosler CC, 31.0 grains CFE223, CCI 450

16" 2449

18" 2471

20" 2526

24" 2619

100 Grain FMJ Wolf

12” 2364

16" 2507

18" 2571

20" 2615

24" 2695

Hand Load 107 Grain SMK 28.5 IMR8208XBR, CCI 41 Hornady cases.

20" 2658

24" 2729

Hornady 123 grain American Gunner

12” 2201

Here is the difference between the 18” barrel compared to the shorter 16” barrel which was slower with every load.

120 grain PPU HP BT

63 FPS difference

110 grain PPU FMJ

60 FPS difference

123 grain A-Max

45 FPS difference

123 grain SST

63 FPS difference

Hand load 123 grain Nosler CC

27 FPS difference

Wolf 100 grain FMJ Steel cased

64 FPS difference


Difference between 20” and 18” barrel 6.5 Grendel

120 grain PPU HP BT

25 FPS difference

110 grain PPU FMJ

44 FPS

123 grain A-Max

41 FPS difference

123 grain SST

18 FPS

Hand load 123 grain Nosler CC

55 FPS difference

Wolf 100 grain FMJ Steel Cased

44 FPS difference

[VASCAR2]

Here is the graph of velocities per inch. I wish I’d had my Son in Laws 22” barrel on that day where we chrongraphed the different 6.5 Grendel barrels. I’d like to do the test again and include my 12” plus Son in Laws 22”.

[grayfox]

Sq, Ballistic Advantage/Aero used to make fluted barrels, SS, that IMO were better than most rack-grades and definitely a few oz lighter - 32 oz IIRC rather than 39-40 oz for most 20" barrels. Had a 1 moa guarantee. I had one at 20" and it was a 1 moa shooter or better for me, but I sold it as I had a few too many barrels on hand. Shot 123 sst's at 2510 fps and did well. 100 gr ttsx too (faster, ~2700) and 90 gr tnt.
If you can find one it may be something to think about, I don't think they make them any more.
They were not too many $$ too, so a good deal.

There are light weight bolt carriers and with a tunable GB you can tame the bolt cycle and save some oz too. Light weight carbine style buttstock, a lighter-style scope vice the heavy 30mm scopes. Leupold 1" dia scope comes to mind, or an lpvo.

I think you're mostly going to find lighter wt by shaving some ounces here, then there, from various parts of the build.
But you definitely want a good barrel, that's what imparts your intentions to the bullet.

And get a good trigger, not a heavy 5-lb pull, that doesn't save wt but can mess up your shot.

Edit to add: a quality 16" like lilja might be more of the shooter you're looking for than a longer medium quality pipe... a 16" will do good hunting out to 250 yds or so, which covers most hunting shots anyway.

[SDW]

Wilson Combat has this barrel at 52oz...

https://shopwilsoncombat.com/BARREL-65-G...SSRG22FT8/

I just bought one of these. Yep, definitely not going to make for any kind of lightweight "upper" setup, that's for sure. Mine's getting a 35 oz Athlon Ares scope too. It'll be more like an artillery piece.

I don't know why you couldn't have a barrel like the above turned down (reprofiled) though. Can be done by either of these companies:

• https://ar15barrels.com/prod/custom.shtml
  
  
• https://adcofirearms.com/products/gunsmi...ionrepair/
  

[dammitman]

you can do this, its mostly about money and availability of needed items,,,mostly money!

[tdbru]

Squirelmarm,
here's the tube i selected for my light(er) weight upper: https://faxonfirearms.com/faxon-20-gunne...-nitrided/ it's 30.7 oz. pretty light weight for a 20" tube. no it's not a match barrel, but shoots well enough for most hunting situations. Of course I do reloading and like to tinker with bullets and loads to get the best out of it. if you're shooting factory ammo, you'll just have to pick up one of every kind you can find and give them a go.

i could have gotten a little lighter weight scope and rings. i have a flat top with rail on my light(er) upper. so i could as well gone with the Leupold fixed 4x (9 oz) and some light weight 1" pic rail rings and might have ended up under 8 lbs. unless prairie dog shooting at long range, a simple fixed Leupold 4x would suffice for big game out to the effective range of the 6.5 Gr. if very light weight is the goal. I have a discontinued Leupold AR-Patrol on it because I picked it up on clearance. And i have a cantilever 20MOA ringmount setup. if i went with the straight Leupold 4x with alloy pic rings, i might be able to shave another 1/2 to 3/4 lb off of my setup. that would likely end up in the ball park weight that you were looking for, so it's not an impossible goal i don't think. I may still do some swapping among scopes/rifles and put a straight Leupy 4x in alloy pic rings on and see just how light i can get with what i have. hmm....

anyway, i think you can end up between 7 and 8 lbs with scope and a 20" tube at least without going to serious gyrations. i'm running a non adjustable gas block. the faxon of course is rifle length gas tube setup. Standard BCG so i didn't get extreme with weight savings there either.

if $ was no object i suspect you could piece part together a 20" 6.5 Gr and get below 7 lbs with scope, maybe close to 6 lbs. but 8 lbs or less is still a very useful weight for a hike about hunting rifle.

good luck.
-tdbru