I have just found what i believe is a bushmaster upper at a local shop... and i was wondering if any upper/lower were combatible even if they were made by diffrent manufancuers. as in could you put any Armalite,BushMaster or any other AR-15 manufancure's upper's and lower's together and work properly?....I am just now geting a bug to get an AR seeing i have been mostly into shooting Ak's n long rifles..

Thanks

-Russel

They are pretty much all compatible. There are some Colts out there with different pin sizes, but you'll know if you run acrossed one of those.

They mix and match pretty good. The biggest issues seem to be having the receivers match in color, and even that's not usualy a big deal.