Unlike BATFE, which made the rules clear on the mag ban . . . they allowed you to replace ANY part, as long as you didn't create an additional hi-cap mag. MGLs are mute about what you can/can't do and it will take a court test case to maybe clarify what is legal and what isn't.
Best guess is that internal parts should be replaceable. Glock will sometimes do that (I'm unsure if they will do it to old mags or not, a call will get you an answer). If not, places like Topglock.com, Brownells and maybe Midway sell the internal parts for replacement. Wolff springs are always a good bet.
Sources of pre-ban mags:
- Well there is some confusion on what exactly is pre-ban. I have info from some trusted sources that indicates that the pictures we've all seen are NOT the definitive answer. On the other hand, Glock-US doesn't know all the minor changes (and implementation dates) that Glock-Austria did and they can't get a straight answer out of the HQ either!
- That said, the most sure thing is buying them from folks on glocktalk.com, ar15.com, etc. I have purchased a bunch of pre-ban G17 mags and all came as NFML U-channel genuine pre-bans.