since the ban is over, am i legally allowed to convert my 10 round mags to 15 round mags? met someone at the range yesterday who also has a USP9, and he had bought about 8 10 round mags at $5 a piece, and converted them to 15 round mags. i shot a couple of his converted mags out of my gun, and they work flawlessly. he taught me how do do it. is it legal to do this or what? just wanna play it on the safe side.