Best barrel length for suppressed AR-10?

[fortify503]

Apologies if this thread already exists, however I could find nothing... maybe for good reason?... just another semi-auto gunner trying to think like a precision bolt gunner? IDK...maybe. I know suppressors vary in design so I'm wondering what I need to consider going into a new barrel purchase to best match an OSS Helix suppressor on a semi-auto AR-10. This will be for a Aero M5E1 chambered in 308 Win. I hand load and only push my rounds to 2550-2600 fps at their current sweet spot (I understand that will be meaningless to a new barrel)... My first inclination is to keep the rifle length gas system but step my 20" barrel down to a 18" barrel. Maybe going 16" barrel mid length gas system would be just as advantageous? I believe the engineers would call this a, Critical Length. IDK, I've only ever shot my 20" barrel rifle length gas system and I'm getting great results out to 950-1,000 yards with 168 gr. SMK BTHP. Anyone have some experience to offer up in this realm? Crap to talk? Thanks.

 

[RyanScott]

16” rifle gas. Intermediate at the shortest.

 

[Merle]

My 16" Criterion rifle gas barrel has been 100% reliable suppressed and unsuppressed. I have a 16" mid length Criterion and it has noticeably more recoil than the rifle gas barrel but 8t has also had no issues running suppressed and unsupressed. Both have SLR adjustable gas blocks but I set them to run with the ammo I'm using with and withoit the suppressor and don't touch it.

 

[smokin.338]

If your running good with what you have, why change anything ? I would look into an AGB and call it a day. That oss design is good with back pressure, not so good on suppression though...

 

[LiveToDrive]

16" but only because shorter requires another damn stamp. I'm also looking for a 16" 308 as a woods/occasional hunting riffle, but undecided about buying and getting it over with, or doing a build. A nice Criterion barrel would make a handy as well as accurate rifle.

 

[RyanScott]

OP, just have your existing barrel cut down. The port may or may not need to be enlarged. Problem solved.

 

[PDXGS]

It all depends on your gas system and the back pressure created by the can and barrel combo.
An adjustable gas block and a variable spring buffer might make your effort easier albeit more expensive.
Have a look at JP Rifles' components.

JP Rifles

 

[fortify503]

If your running good with what you have, why change anything ? I would look into an AGB and call it a day. That oss design is good with back pressure, not so good on suppression though...

The design of the OSS shouldn't require an AGB. Your right, it isn't the quietest can out there. Honestly Im interested in maintaining accuracy out to 1,000 yards like I currently achieve but stepping down the length because a 7" can atop a 20" barrel wont even fit in my gun safe with the shelf the way it is haha...

 

[fortify503]

It all depends on your gas system and the back pressure created by the can and barrel combo.
An adjustable gas block and a variable spring buffer might make your effort easier albeit more expensive.
Have a look at JP Rifles' components.

JP Rifles

I am currently running the JP silent capture buffer spring. The OSS is ported in the front and shouldn't require an AGB. mainly I just wanted to see opinions on stepping down the length while still being able to maintain my accuracy out to 1,000 yards. Pull me, the shooter, out of the equation and it sounds like 16" rifle gas system will provide as long as I do

 

[bghartm]

I run a 16" proof research barrel with JP adjustable gas block and silent capture spring. I would not trade it for anything on the market. I have only shot it out to 200 yards so far but it performs flawless with the block adjusted properly. I have to give it about a 1/2 turn when going from suppressed to non-suppressed.

 

[Darqusoull13]

With the OSS you're going to be about as close to unsuppressed as it seems you can get with a suppressor in terms of back pressure. 16" might require a heavier buffer and some gas adjustment but I would NOT go rifle length for this. It's hard enough getting a 223 rifle length gun to run without a can. 18" rifle shouldn't be too difficult but might also require either buffer or gas tuning. 20" rifle should be much easier.

Everything WILL benefit from tuning though. The question is, what do you want to tune the rifle to do? Are we talking only on paper/steel out to 1000? Go 20" and make your life easy. Is this a game gun where you need to be able to spot impacts to correct in a match? Again, 20" but a slightly different tune with different parts. Will this be used for back country, blind or hog hunting? Now there's a good reason to have a shorter rifle and a 16" makes sense.

 

[fortify503]

With the OSS you're going to be about as close to unsuppressed as it seems you can get with a suppressor in terms of back pressure. 16" might require a heavier buffer and some gas adjustment but I would NOT go rifle length for this. It's hard enough getting a 223 rifle length gun to run without a can. 18" rifle shouldn't be too difficult but might also require either buffer or gas tuning. 20" rifle should be much easier.

Everything WILL benefit from tuning though. The question is, what do you want to tune the rifle to do? Are we talking only on paper/steel out to 1000? Go 20" and make your life easy. Is this a game gun where you need to be able to spot impacts to correct in a match? Again, 20" but a slightly different tune with different parts. Will this be used for back country, blind or hog hunting? Now there's a good reason to have a shorter rifle and a 16" makes sense.

Just to clarify this will be for a .308 AR-10 semi-auto. Im running a JP-silent capture buffer spring. No adjustable gas block yet but just to be sure, are you saying if I go 16" barrel to run a mid length gas system and not a rifle length gas system? Thanks for the input!

 

[fortify503]

I run a 16" proof research barrel with JP adjustable gas block and silent capture spring. I would not trade it for anything on the market. I have only shot it out to 200 yards so far but it performs flawless with the block adjusted properly. I have to give it about a 1/2 turn when going from suppressed to non-suppressed.

i take it you're running one of those suppressors that actually reduces the decibles out the barrel and thus have some hefty back pressure? thanks in advance