Suppressors 338 Federal Suppressor Set-Up: Help / Input Requested

[TXCOWDOC]

Hello-
I have an Armalite AR-10 in 338 Fed. 22" Barrel, 1:10" Twist. I also have a YHM 338 Phantom. I realize what I give up by shortening the barrel (velocity, potential gas pressure changes, etc). This will be a dedicated suppressed project. Here's where I need some guidance:
1. Hand-guard- What would you go to? I don't like the black tube.
2. Adjustable gas block?
3. Barrel length (minimum of 16" as I don't want to SBR.)

I have a competent smith to cut/ crown / thread. Thank you for your replies / advice-

 

[KYS]

I'd probably keep it around 20"
You will most definitely need an adjustable gas block or buy a Noveske Switch block and have the smith tune the ports to your load.
Hand guard could be anything you like that is compatible with the AR10. I like Centurion Rails as of lately.

 

[jasonfaz]

That'll be a fantastic rig! What length is the gas system on your barrel? If it's mid-length I'd absolutely go 16". If it's rifle length I'd go 18". The .338 Federal is an extremely efficient cartridge and one that doesn't benefit greatly from a longer pipe. I'd highly recommend the 15" Midwest Industries SS Keymod handguards. They tip the scale just a hair over 14 ounces.

Per the adj gas block, even if your barrel has a .750" gas seat that is at least 1.9" long - which is what you would need to run a Switchblock - I think there are far better options considering your intent to use it suppressed whenever possible. I would see little value in using a Switchblock unless you foresee constantly switching back and forth from suppressed and unsuppressed. It might require machining the handguard to cover it and it's significantly heavier than other options that fit your application better. A far superior choice would be grabbing an SLR gas block and tuning it to your rifle and specific loads. They're available in .625", .750", .875" and .936" diameters. It would also save you about $70 or so just on the gas set up. You probably won't even need to adjust for much if you go down to 16" from 22" as the gas port should be significantly smaller in diameter than a 16" barrel from the factory. PM me if you have any specific questions as I've gone through the suppressed 338 Fed project three times now. It's an AWESOME set up. Here's my most recent .338...

 

[TXCOWDOC]

Jason-
You're the guy I've been needing to run across. This one is rifle length. So 17-18" minimum length. My main concern is overall length as the Phantom is 10" long. That is why I wanted to go as short as possible (within reason) on the barrel. I'll PM you my cell. I'd like to visit if you've got some time.
Thanks again-

 

[jasonfaz]

You bet my man. I'll give you a ring sometime tomorrow when I get a little down time.

Until then, I think your set up will be damn near perfect at 18 inches with rifle length gas. If JP offered their 18" Supermatch .338 in rifle gas that's definitely what I'd be running. My can is 9.5" in length and isn't a huge deal for what the rifle is. The key for me was making the weight manageable, which is very doable with what's available today. Talk to you soon...

 

[TXCOWDOC]

AR goes to smith this week. Still undecided on length. Longest will be 18". Armalite SASS hand guard and adj. gas block arrive tomorrow. Looking forward to the finished product.

 

[TXCOWDOC]

Jasonfaz-
What size gas port do you have on your 18" barrel? My barrel was cut from 22" to 18" and threaded 5/8-24. I installed the Armalite SASS hand guard / adj. gas block. I talked to the Armalite Tech and he suggested leaving the 338 Fed gas port same and testing 1st. So I did that. Put a couple rounds of Fed 185 grain (MV 2750 fps) through it. Not enough gas to lock the bolt back on a single shot. So now I will enlarge the port incrementally until the action cycles properly unsupressed.

Current port size on the 338 22" Barrel is .082". Typical AR10T 308 is 0.088". SASS systems are 0.099" on 18" barrels.

 

[jasonfaz]

I'd test it with 200s and 210s before enlarging. This is with your can on right? My gas port is .096" but keep in mind it is mid-length not rifle length. Mine is also turned down a LOT. Yours should be good to go .082" with full power ammo. What spring/buffer are you using?

 

[TXCOWDOC]

TO evaluate the effect of barrel shortening, I fired the full power ammo without the can on. Gas selector was set on normal. I have factory (armalite) spring / buffer.

 

[jasonfaz]

Give me a call later this afternoon...

 

[dmtsc]

How short of a barrel could you run and still have an efficient powder burn? Interesting project and one I've thought about just never seen anyone with suppressed 338 Federal.

 

[jasonfaz]

Depends on the bullet and powder being used. Generally 16", but you can get complete burn in 14.5" give or take a half inch, using 160 gr TSX.

 

[dmtsc]

Does your 338 can have the 90 tooth mount? If it does how's the repeatability when taking it on and off and does it stay tight? I've shot some wild boar with 85 gr tsx out of 243 it would amuse me to do the same with .338 160 gr tsx. Those pesky bears on my farm might also be a good target/experiment.

 

[TXCOWDOC]

Thanks Jason. I'll run some 210s and see how it cycles. I'll keep you posted.

 

[jasonfaz]

It does mount to a 90T brake. The newer design of the 90t cans really does a good job keeping carbon build up from the teeth. I admit that I do lightly run a wire brush over the teeth on this mount about every 500 rounds or so only because I got accustomed to doing so with the 51T mounts for repeatability purposes. But to answer your question, with 1,200 or so through the can, it locks up tight in the exact same place every time. I put notches on the back of the can and mount where the can locks before ever shooting it so that I'd be able to visually notice any alignment issues and it's never needed any attention.

Those 160s would be interesting to see on black bear. I've always used the 200s. The lack of recoil on this thing still surprises me every time I take it out. Very efficient cartridge indeed!

 

[jasonfaz]

Thanks Jason. I'll run some 210s and see how it cycles. I'll keep you posted.

You bet buddy, I'll shoot over some load data here shortly.

 

[rlsmith1]

Looks like Jason hasn't been on for a while so posting here rather than PM-ing him.

To those of you who have suppressed a 338 Fed, what was the preferred suppressor length? I'm looking to do a Form 1 or possibly go through Rex Silentium to have one built for it. I'm thinking something in the 6" to 8" range but don't know if that is too short or if shorter is possible when using subs.

 

[HansohnBrothers]

Looks like Jason hasn't been on for a while so posting here rather than PM-ing him.

To those of you who have suppressed a 338 Fed, what was the preferred suppressor length? I'm looking to do a Form 1 or possibly go through Rex Silentium to have one built for it. I'm thinking something in the 6" to 8" range but don't know if that is too short or if shorter is possible when using subs.

Get a Rex Silentium ModX 338

Rex Silentium MOD X .338 – Hansohn Brothers

hansohnbrothers.com

 

[rlsmith1]

That's my plan but also want to have something I can run on 338 mags and I prefer (I think) to have something that will suppress better so I will likely end up with something longer than 8.8". I've looked at TBAC's 338 design as well as the Surefire 338 and the dedicated 338 mag cans seem to be more in the 10" range.

I'm sure you guys have run the Mod X on a 338 Lapua, how did it do?

 

[rlsmith1]

Looks like a sweet can for sure, are specs listed somewhere that I missed them? Excited to see guys using 3D printing for this stuff