Cut me some slack Ive been searching around and havent found to much info. I just built my first ar using a delton kit and dpms lower. I was noticing on deltons site they have a 300fireball and 7.62 upper. My question is can i just take my ar15 upper off and just interchange these uppers on to my dpms lower or do I need to buy a different lower? Also what do you do about mags will the ar mags work or do you have to buy custom mags? Sorry for all the questions but the only thing I could find info on was the .22lr conversion.

should.

For 7.62x51 (.308) you need a new lower because the round will not fit in the magwell.  For 7.62x39 you can use the same lower and mags as .223, you just won't fit as many in there.  .22 will use the same lower as .223.