View Full Version : .300 Blackout Upper suggestions....

09-07-2016, 03:19
Came in to some ammo by chance and finally decided to get a .300 BO upper. Any advice from those that have them? Looking for a shorter barrel on a select fire lower and will be using a Surfire SOCOM SPS most of the time with it. So many options out there and appreciate all opinions.

Thanks in advance,


09-25-2016, 06:47
I use a 12.5" 5.56 upper from BCM and would purchase their 9" 300blk upper in a second. In fact, that is going to be my next firearms related purchase. So, I cannot speak from experience, but at 9" it should permit full burn of the powder, and BCM quality is solid.

The Reaper
09-25-2016, 07:56
Concur. BCM makes some fine gear.

The pistol length gas system is the way to go with the .300 BO.


10-02-2016, 10:56
Was trolling around on GunBroker and decided to go with a 300 pistol upper from PMA.


Went with a 10.5 inch barrel with a 1/7 twist.

Returned very happy from the range yesterday as my new upper and pistol lower from Rock River matched up perfectly.

Price was not steep, and after 100 rounds or so I had no failure to feeds/eject.

I did not purchase a new bolt or charging handle, so it helped with price.

I'm researching loading data now, but I primarily ran subsonic ammunition on her first outing.

Pretty happy camper right now.

11-02-2016, 02:50
Ended up going with a Black Rain slim rail m-lok upper 10.5". Was debating between it and the BCM, but I'm not a keymod fan and this fit the bill. Crazy quiet with sub loads and kept it light and pretty simple. MRO red dot does a great job and a .45 offset Surfire mini 300 scout sits just right. Still playing with handstops and stock but the adjustable gas system works well and it's dialed in now.....just a few tweaks left. Too bad the ammo I came in to wasn't nice quality subs but I won't complain. Definitely prefers DD mags when using the expensive sub rounds though to pmags. I'll post a pic of the finished product when complete, but Black Rain has built a quality upper that I'm glad I gave a chance.

Thanks again for the replies,