Anyone using a 26" barrel on AR10?

[picone]

Does anyone have experience running a 26" barrel or an opinion on barrel this long on an AR10?

Mostly interested in how it relates to accuracy. Cycling is not an issue. Current trend is that everyone runs a 20". I've even been told once that the attachment of the barrel isn't strong enough to hold a longer barrel than 20" (clearly not the case since DPMS and GAP offer). GAP offers a 24" but all the one's I see are still 20". Just curious if anyone has experience with this. Thanks.

 

[scotharr]

Re: Anyone using a 26" barrel on AR10?

Highpower shooters use 26" barrels with the gas port pushed back 2" to 4" depending on the cartridge and powder used. It's a normal option.

 

[ORD]

Re: Anyone using a 26" barrel on AR10?

It is unlikely that you will perceive a difference in accuracy going from a 20" to a 26" barrel (at least with a 308). What you get from the additional barrel length is a modest gain in muzzle velocity which in turn, leads to an increase in usable range of the rifle.

As for what you have been told about the receiver not allowing for the longer/heavier barrels...nonsense! I have owned a couple of different 308 semi-autos (one built on an Armalite and one built on a DPMS) with longer barrels. The Armalite had a medium-heavy, 24" barrel chambered in 308Win Match that was roughly 1.1" under the HG, 0.875" at the junction, and 0.8" to the muzzle. The DPMS had a 26" barrel with roughly the same dimensions, but with the gas port moved forward 2".

Frankly...it is just additional barrel length, muzzle weight and no real gain for any practical application for any of the shooting I was doing with either of the rifles. My 20" barreled 308 semis will get to 1k accurately enough to bang steel all day long and I don't have any need for shooting any 308 further than that. I built them "because I could" and I wanted to try longer barreled 308 semi-autos. I just sold the last one (Armalite) earlier this year and I have no interest in going down that road again.

Here is a link to another company that offers AR-10/LR-308 uppers and complete rifles in numerous calibers with up to 26" barrels.

http://www.ar-10-rifles.com/index.php

 

[wildbill9ball]

Re: Anyone using a 26" barrel on AR10?

i have an ar10t that WOA built and it is 26 here is a link to it

http://www.snipershide.com/forum/ubbthre...813#Post1669813

 

[picone]

Re: Anyone using a 26" barrel on AR10?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ORD</div><div class="ubbcode-body">It is unlikely that you will perceive a difference in accuracy going from a 20" to a 26" barrel </div></div>
People I trust more than the other have told me the same. Just checkin'.

I put a lot of effort into this build and it doesn't hit the broad side of a barn (5-6MOA). I traced this to a different issue which will be rectified this week. Not sure when i will have a chance to go test it again, after the fix.

 

[frankythefly]

Re: Anyone using a 26" barrel on AR10?

going from a 20 Inch to a 26 inch barrel You can expect a min of 134 FPS to a max 200fps depending on twist, chamber. 6mmbr.com talks about this in the .308 section.

 

[JL]

Re: Anyone using a 26" barrel on AR10?

Im shooting Oberland Arms OA-10. It used to be with 26" SS Lothar Walther barrel.
Same barrel was shortened to 22", and 155 Scenar accuracy improved from 1MOA/5 shots/100meters to 0,7MOA. MV went from 2930 to 2805 thought havent tried limits with current setup. Using Lapua Palma (Small rifle primer) brass now- reloaders only choice for AR10 system IMO.

Contour was updated at same time, from 22mm (0.875") bull to 20mm.
185gr Scenars shoot 0.5MOA, as they did before shortening, but cant get enought velocity with them. 155 is still ballistically best choice.

26" barrel is too long for practical field rifle IMO, thats why I went with 22".

 

[picone]

Re: Anyone using a 26" barrel on AR10?

Good info, thank you.

 

[BasraBoy]

Re: Anyone using a 26" barrel on AR10?

OP - not quite an AR derivative but I run a 26" heavy barrel on my AW .308

Velocity is maintained supersonic out to 1000yds but I would not want to use it as a stalking/hunting rifle....weight aside it is LONG!

 

[azerious85]

Re: Anyone using a 26" barrel on AR10?

I should be getting an 18" LR-308 today, i'll let you know how she performs

 

[BCP]

Re: Anyone using a 26" barrel on AR10?

Lots of people running 24" DPMS 308's so I don't see why a 26" wouldn't work. If you're shooting long range I think that would be the way to go. Once you get optics and everything on it you are probably talking a 20+ lb rifle though.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: azerious</div><div class="ubbcode-body">I should be getting an 18" LR-308 today, i'll let you know how she performs </div></div>

They shoot great (with a hot barrel I was making 1.5-2" groups at 200, cold is 1-1.5" center to center depending on how steady I am) but they are heavy. I think my 18" wannabe sass is 15 lbs.

 

[Greg Langelius *]

Re: Anyone using a 26" barrel on AR10?

I like longer barrels. I believe there's a significant relationship between case capacity and bore length, probably as an expression of expansion ratios.

This affects a lot of things and the ones I like to pay to pay attention to mostly all relate to throat life. I like to run the engine room at something significantly less than full throttle. My view is that a longer barrel allows one to reach a target velocity while running the throat at less pressure and temperature.

I also think that once sufficient muzzle velocity is reached to allow the the projectile to reach the target at, say, roughly 1250-1300fps, additional velocity increases will produce diminishing returns.

The thing that troubles me is what's happening to the bullet jacket inside the bore while those additional velocities are being generated, and how this relates to fouling rates and accuracy degradation over the full length of extended strings of fire.

Keeping the numbers down just seems to me to be a better approach, and the longer barrel just seems to lend itself to less energetic approaches to these problems.

As a target competitor, such approaches need to cope with issues relating to the long run and many shots.

This elevates some issues to a level of importance that is very different from the needs of the extended, extreme range marksman who banks on achieving one's goals with a minimal number of shots. I don't see even the most current crop of semiautos as the most ideal choice for such applications, but I also do believe they are getting a lot closer to such goals. I think longer barrels are going to help in that process.

Greg