1) What is a good brand? Best brand for the money thats still reliable? (Disregard "black friday" "deals" just looking for comparison at "normal" market prices) 2) Also are all "Pmags" interchangeable even between different manufactures? or do you HAVE to buy the colt mags for the colt AR? 3)Building VS buying complete. Is it easy to DIY or does it require gunsmith? Thanks!