Compatability of Uppers to Lowers

[Bruce]

I have a Bushmaster RAW and want to put together another upper for it. Are upper receivers other than Bushmaster's compatable with a Bushmaster lower? Are there brands that are more compatable with Bushmaster than others?

[TMC]

All mil-spec (non-Colt) should fit. Almost all have a bit of movement between the upper and lower even of the same manufacture.

[THT]

All other in-spec uppers will fit your lower. Years back, Colt made "big pin" rifles which wouldn't work with your BM.

[Bruce]

Thanks guys. Any recommendations for flat-top uppers? Any brand to avoid?

[Ed_Hazard]

I've got several Stag 2htl's on acouple of my XM Series BM and they work fine, no rattle or play, some daylight but thats the nature of the beast. For 20" uppers I went with a Armalite HB flattop and love it. The next one I upgrade will be with a DPMS Dissipater upper.

[gmcal]

Thanks guys. Any recommendations for flat-top uppers? Any brand to avoid?

Intended purpose of rifle? What kind of ammo (bullet gr) will you shoot? Will you use any optics?

For an upper with 16" 1:9 twist barrel my preference is S&W.

For an upper with 16" 1:7 twist barrel my preference is BCM.

There are other good choices but I don't have first hand experience with them.

[bohoki]

standard uppers should fit standard lowers but sometimes acceptable tolerances compound and minor fitting may be required

[Blkrifleshaggy]

Im going to point you in the direction of Daniel Defense and BCM. I would say go with 1:7 on the barrel so you can fire some of the heavier grain stuff without tumble. Also what " barrel are you going for. if 16" i look at a middy gas system as well. but honestly this might be overkill for us in california. but i love the piece of mind.

smartgunner.com
bravocompanyusa.com
riflegear.com

a couple of my go too's.

[hollowpoint]

It's hit and miss on the fit of uppers and lowers, so it seems. I have a stag on stag that has no play what-so-ever yet a spikes on spikes that warrants an accuwedge for proper fit.