Hello all. New member, first post, and I appreciate any insight. Monday I picked up my first Glock, a G30 with OD frame. Also picked up a Glock-factory G21 magazine the dealer had as I intend on using it as my secondary mag when carrying concealed. The 10 round mags that came with the pistol drop free with no problems, but the G21 mag seems snug when inserting and requires a tug to fall from the mag well. I have compared the magazines side by side and it appears the G21 mag is just ever-so-slightly wider than the 10 rounders. I can't comment on feeding reliability as I have yet to get to a range to test the pistol. My question is basically this: Can the G21 mag be sanded down a bit to thin it, or is this asking for trouble? Thanks in advance for any assistance, and take care.