If you are going that route get into Unimags. You can buy gen II mags for like 20 bucks right now and they fit most calibers up to .458 SOCOM and it goes into a AR lower. So you don't have to get lots of different mags and they can be used reliably between your rifles no matter what upper you have on them. So if you print a lot of lowers or get different caliber uppers.