AR10 barrel length help?

[clearconscience]

I'm trying to decide on a barrel length for my first AR10 build.

I'm think I'm set on the Faxon Arms in a 5R, but not sure if I should go with a 16, 18, or 20" barrel.
I'm not looking to shoot 1000 yards, but want to be able to use it for hunting.
Would 2-4" make a big difference?

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[slimmer13]

I've been seeing a lot of cut down .308s. Testing I've been reading about says .308 seems to lose less velocity per inch than a lot of other calibers (20 to 30ish fps). I would get the 18" personally for the middle of the road velocity/ maneuverability.

308 Winchester / 7.62x51mm NATO: Barrel Length versus Velocity (28″ to 16.5″) (http://rifleshooter.com/2014/12/308-winchester-7-62x51mm-nato-barrel-length-versus-velocity-28-to-16-5/)

 

[IronMonster]

I have .308 AR's in 16" 18" and 24"

Honestly the one that gets shot and I find most enjoyable is the 16" The 24" is to heavy for anything but sitting on a bench and really does not shoot discernibly better than the 16" with me shooting factory ammo (the 16" is capable of 1.5-2 MOA at 400 yards which is as good as I can shoot with anything)

 

[Vorpalis]

Figure the longest shot you're likely to take where you hunt. Then lookup the minimum expansion velocity for the bullet(s) you think you'll use. Using the info in the Rifleshooter.com link slimer13 mentioned, calculate the barrel length you should get.

 

[mjbskwim]

20"

 

[Boboclown]

Unless you're going past 300 yards a 16" barrel will be good to go for the most part. Keeping it as short as possible helps a lot if you ever have to go into thick brush. It being lighter also helps.

 

[Mark W.]

I have read numerous articles stating 22" long is the sweet spot for .308 rifles it has to do with the harmonic's.

YMMV

 

[mjbskwim]

I have read numerous articles stating 22" long is the sweet spot for .308 rifles it has to do with the harmonic's.

YMMV

What would be nice is to get all the engineers on the same page

 

[clearconscience]

Yeah I think the problem is there are too many factors that play into it. The .308 isn't the best long range cartridge anyway.
I'm pretty sure I wouldn't be pushing it out past 300yds. I just can't see that damn far. In the Northwest, mainly SW Washington there isn't much room for long range hunting any way.

For me I think the 16" would be fine.
The weight isn't a dramatic difference maybe 1/2lb, and neither is the drop in velocity over a 4" barrel difference.

 

[Boboclown]

If not going past 300 yards then definitely go with the 16" barrel.

I have read numerous articles stating 22" long is the sweet spot for .308 rifles it has to do with the harmonic's.

YMMV

In theory, yes. In practice, barrel length doesn't really matter much beyond velocity. If anything, one could reload anyways to make the barrel length negligible.

 

[clearconscience]

Yeah I'm not really going for long precision. I don't reload and factory loads are only so good.

Trying to keyhole at 600yards with factory ammo is not going to happen.

At least that's my excuse.

 

[Velzey]

I shoot two Remington 600's with 16" barrels chambered in .308, and hit a 7" wide steel gong at 600 yards easily!

I like shorter barrels in .308!

 

[clearconscience]

Teach me!

Just kidding. My problem is lack of practice. I only get out a couple times a year, so my flinch and trigger control suck. I just need practice.

 

[Bretts300aac]

I think 16 is fine I have one and an 18 both are scary accurate on My lr 308 longer you go the nicer they are to shoot or just get a can on the end of that baby and really enjoy shooting

 

[Robtheroofer]

I personally am going with a 20. Weight can be raised or lowered by the type of barrel so to me 20 inch does not weigh hardly any more than 18 or 16 even, depending on barrel choice.

I don't care about maneuverability in a 308. I am building mine to reach out and touch something.

Got a 12 guage and handguns for home defense so I can't see a reason for me to go short for a 308 barrel.

Go 20 or even 22 inches. Just my own opinion.

 

[clearconscience]

Well I'm probably going to switch this to my hunting rifle so weight and maneuverability is important. I'm hunting in the woods so not too worried about having a long range shot.
I might down the road buy another upper in something longer for the versatility. But that will really just give me a reason to build another one.

 

[Robtheroofer]

Well I'm probably going to switch this to my hunting rifle so weight and maneuverability is important. I'm hunting in the woods so not too worried about having a long range shot.
I might down the road buy another upper in something longer for the versatility. But that will really just give me a reason to build another one.

I feel ya, that's why they make different sizes. One works for you and one works for me.

I have already been looking at light weight upper options in a shorter barrel.

I ended up with two buffer tubes so I guess I have to build another AR, can't waste a whole buffer tube.

 

[B5Ben]

I went with a 20" and like it, but have not shot an AR-10 any shorter to compare. Weight isn't bad and I like having it there for recoil reduction and quicker follow ups. I think you will be fine in any one you choose, just get one and start working it over. You can always change it out later if it really isn't what you want.

 

[U8395279]

Yeah I think the problem is there are too many factors that play into it. The .308 isn't the best long range cartridge anyway.
I'm pretty sure I wouldn't be pushing it out past 300yds. I just can't see that damn far. In the Northwest, mainly SW Washington there isn't much room for long range hunting any way.

For me I think the 16" would be fine.
The weight isn't a dramatic difference maybe 1/2lb, and neither is the drop in velocity over a 4" barrel difference.

There are still lots of other factors to take into consideration, than just the length of the barrel.

What is the barrel's contour going to be? There are lots of different contours, and that will also affect weight and balance.

Then there is the twist rate to consider. What bullet weights you want to shoot, and how long the barrel is will influence what would be most ideal twist for you to have in your barrel.

And finally there is the gas system. What length of gas system will the barrel have on it? Have you considered that yet?

You still have a lot of work ahead of you to figure out.

I would not go with a FAXON barrel myself personally, since it is designed specifically for max accuracy out of 308 Winchester spec ammo. FAXON themselves will not guarantee function with 7.62x51 NATO ammo, as they note on their website, in the following text:

====================================
*Note - Faxon Firearms barrels are chambered to SAAMI specification .308 Winchester to a nominal headspace depth (passing "Go" and failing "No-Go"). This ensures maximum safety and accuracy.

7.62x51 NATO is not the same round as .308 Winchester, though it will fit within chamber. 7.62x51 technically requires deeper headspacing to meet the military specification and is known to function in Faxon .308 WIN barrels under most circumstances.

However, due to the variation of components in the .308 AR world and variations between loadings, Faxon cannot guarantee or warrant function with 7.62x51, especially with bolts with tight ("match") .308 WIN headspacing.
====================================
.

I bought this barrel by Criterion at the link below instead.

Although its specs are similar, the barrel does unfortunately cost $100 more than the FAXON. But it does have a Hybrid Match Chamber that they say is compatible with both .308 Win & 7.62x51 mm NATO ammunition. Plus it is also chrome lined.


Barrel, 18.5", .308 AR, Light Weight, 1x10, Chrome Lined, Threaded, Match Quality, FA by Criterion (http://www.fulton-armory.com/barrelfatitan185lwcm1x10750gasblockchrome-lined.aspx)
.

 

[H2O MAN]

16 or 18