I am looking for some good metal magazines to compliment my stash of pmags, preferably steel instead of aluminum. I know steel mags will weigh more, but I recently got to handle a friend's mini 14 all-steel mags and they just felt like some good, quality magazines. I am hoping to find something similar for AR's. I remember reading somewhere that HK mags are considered some of the better, if not best, metal mags on the market. Are they all steel, and are they worth the extra cost? Also, can they benefit from a magpul upgrade kit or would that be pointless?

any help is appreciated :)