Can anyone tell me with absolute certainty the letter of the law on this? I have the opportunity to purchase 2 unmarked 13rd usp9c hi-caps at a very nice price, and want to find out if I can use them legally. I know the USP Compact wasn't in the US until post-ban, but perhaps there are some unmarked mags from Europe that are pre-ban? Any light that anyone can shed on the subject would help. Thanks.