300 Blackout SBR

[tom12.7]

When building an upper, how much emphasis is on the quality of the parts AND span of operation? Adding an unknown to the mix may have a negative aspects added to this, but it's an "unknown".

[Waylander]

[CanineCombatives]

I"m at the same juncture right now, 8" or 8.5" is where I want to be with the barrel with a 12" handguard
covering about 3/4 of the can, based on everything I've seen the seekins SPRO is the best route, I'm going
with the new Mlok MCSR and using a different BCG.

[RWCRaiden]

Just a quick question regarding a stamp, if I have a 5.56 registered lower, and I put a .300 blk upper on it, is this still ok under the registered stamp, or do I need to register another lower for the .300blk? Thanks.

[FAB45]

When folks ask me about getting into a 300 Blackout SBR, I normally try to emphasize about what could be gained by piecing things together than buying a quality upper like an AAC or KAC. Some put price out front, but the gamble is still there in span of function compared to a known item. How do they know that they aren't making a very selective decision on a price without a reduction in proper operation? In the 5.56 realm, there are many ways to make a headache. Why jump into unknown territory is so blinded for some?

ETA: I can't type to save my life.

I am by no means going the cheap route. I am just having fun learning a new build. I have bought all quality parts so far, so far it would have been a lot cheaper to buy a complete sbr but this is fun and I am picking and choosing some of my favorite parts. My $350 Noveske barrel wasnt cheap!

[domestique]

Just a quick question regarding a stamp, if I have a 5.56 registered lower, and I put a .300 blk upper on it, is this still ok under the registered stamp, or do I need to register another lower for the .300blk? Thanks.

As long as you are not making a PERMANENT change (i.e. switching out the 5.56 barrel) you are fine to put any upper you want on top of the lower as long as you still have the original upper in your possession.

I have multiple lowers, but filled out my paperwork for the same 1 upper in my possession. This allows me to sell any other SBR uppers I buy and use, and not have to fill out any additional paperwork.

[InfiniteGrim]

I agree to a point. I am looking to buy a Noveske bbl with gas block and tube. I have a BCM upper, sightts and a new BCG and CH. I want a BCM rail but there all sold out. I don't need to spend $800-$1,100 for an AAC or KAC upper to have quality upper.

My friend LOVES cheap barrels. He has 2-3 10" .300 blackout SBR's, all have $100 barrels. His subs are having function issues.... because the chambers are not cut correctly. I use the exact same projectiles in my Rainier .300 blackout barrel with no issues... he purchased one and now plans on replacing all his cheap barrels. So instead of saving $150 per barrel, he is now out $100 for each he has to replace.

[JPB]

I just built a .300 SBR. I went with a Noveske 8.5" barrel, Aero Precision receiver, Colt BCG, SiCo Saker 762 brake, and I know everyone on this site is going to slay me for this but, a UTG Pro keymod 7" rail. I would not hesitate to buy another one of those rails either. Fit was perfect, bolted right up, and is super slim/low profile. Was really suprised by the quality of the unit.

I've only put a box of 220 gr subs through it, but it worked perfectly. Now waiting for the Saker to get out of jail...