El guapo

Can I just ditch the receiver itself and use the bolt and barrel that came with it and not have any problems? Or does everything on the upper need to be replaced?

So I bought a PA-10 complete upper but couldnt find a lower to go with it so I picked up an aero lower with a dpms lower parts kit, rifle length buffer tube, and rifle length dpms buffer. Upon assembly the bolt carrier group is scraping on the buffer and damaging it. I also cant get the pin in to close the upper and lower together. Should I get an aero upper and swap the barrel, forearm, and bcg onto it or should I buy a PSA lower and switch parts to it? Is there a 3rd option? Thanks in advance.

Hello everyone, glad to be here. Im building my 1st .308 AR and need some help and advice. Ive been shooting 3 gun for the last 7 years and I've decide to step up to the heavy divisions. I'm having a problem with my build so I'll head to technical forum and post it there.