.300BLK SBR Build Questions

[LargemouthAss]

I have an Engage Lower that has been registered as an SBR and I am planning a new .300blk upper to use intermittently on the lower. I have a Griffin Armament 30SD suppressor in ATF limbo that I plan to use with this upper (and several other .308 guns). Ideally I would like a 9.5" barrel but I am willing to go to 10.5" if it means less chance of a baffle strike with subsonic ammo. I would like it to run both sub and supersonic ammo suppressed and un-suppressed but most of the shooting will be done suppressed with subsonic ammo at 50-100 yards.

I know I need to go with a pistol length gas system and I know I should get a 1:7 or 1:8 twist barrel, other than that I don't know what I want or need. I am interested in a piston gun since it means less gas in my face when shooting suppressed plus all my other ARs are DI so a piston gun would be something a little different. I am not dead-set on a piston gun so feel free to talk me out of it... If I go piston do I need an adjustable gas block? Do I need an adjustable gas block if I go DI? Any advice is greatly appreciated as I have never built an upper before (although I have built 8 lowers) and want to avoid making any dumb mistakes...

 

[F-Stop]

Was the lower registered prior to the 29" plus OAL requirement? If not, that will change what barrel, stocks you look at.

 

[LargemouthAss]

Was the lower registered prior to the 29" plus OAL requirement? If not, that will change what barrel, stocks you look at.

I live in VA

 

[F-Stop]

Settles that.

Search carrier tilt for piston guns. I have not looked in years but this can be an issue.

Adjustable gas is a plus and since you're building it a good idea. I run a 8.2" Noveske without one and don't have issues with subs or supers. I do sometimes want more handguard length though.

 

[jimbobborg]

I'd avoid a piston upper, but that's just from listening to Clandestine, who gave several good points about their disadvantages. Since you're in Virginia, have you signed up on Virginia Gun Trader yet? There are some good deals on there from the vendors on 300 uppers.

 

[outrider58]

With a piston or di you'll want an adjustable GB. With a piston gun you'll be left with a GB with only two settings a suppressed and not suppressed which sucks. With a di gun, you will want an adjustable GB but you can have a GB with unlimited adjustability which is highly preferred. My advice, stay direct impingement.

 

[LargemouthAss]

Thanks for the advice guys. After reading what Clandestine had to say about piston guns I will stick with DI!

 

[LargemouthAss]

So I just ordered a Noveske Lo-Pro 10.5" barrel and a Noveske stripped upper. Now to pick the handguard, charging handle, BCG, and gas block...

 

[outrider58]

So I just ordered a Noveske Lo-Pro 10.5" barrel and a Noveske stripped upper. Now to pick the handguard, charging handle, BCG, and gas block...

Your bbl didn't come with their GB?

 

[LargemouthAss]

Your bbl didn't come with their GB?

Oh crap, it did. And I do not think it is adjustable....

 

[outrider58]

Oh crap, it did. And I do not think it is adjustable....

They have one but it's an on-off type IIRC. A lot of people use and like them, but it was the reason I went with the Rainier bbl instead.

 

[teratos]

I have a 10.5" Noveske on mine. Using the Noveske non-adjustable gas block. No problems at all with supers or subs.

 

[Semper Noctem]

I've got the 8.5 Noveske and have no problems with subs or supers. It's a great barrel and unlike my 10.5 inch and 16 inch Noveske's, it isn't over gassed. All shells kick to the 4 o'clock.