300 BLK and 5.56 guns

[KHickam]

Howdy I just bought a 5.56 upper from PSA. I have a 300 BLK complete gun I built using PSA, Aero and Anderson parts all mil-spec stuff (they say) and was wondering do you guys just carry a double upper using the same lower or do you have two dedicated rifles. I have a couple extra stripped lowers and LPK and parts to make another lower including extra BCG

What do you recommend?

[Surgeon]

I've had an AR for a number of years and this past January I purchased the 300 BLK Out upper from Radical Fire Arms here in Houston. BTW...I love that round. But, no I just switch them out from time to time because I didn't want the hassle of the background check and transfer cost for just the lower although the costs for a new lower is really not too bad. Just my little protest I suppose. Maybe when I get tired of the 5 minutes it takes to switch out the uppers I'll come around. Until then...Just the one.

[SigM4]

Given that you have the extra lowers and LPK, never hurts to build up another lower for the 300 BLK upper. This gives you the ability to fine tune such things as springs/buffers for each round. Keeps things simpler (to me) and helps me build each lower with a specific role in mind.

That said I do swap out several uppers on one of my SBR'd lowers. I have several SBR'd AR-15 lowers, most being semi-permanently dedicated to a particular upper. One of the lowers however is my host for all sorts of random uppers, among these are a 9.25" .22lr upper and an 8.5" 300 BLK upper. It's my fun fun if you will, playing host to whatever I may want to try out or be fixated on at the time.