I don't know the answer to that, but if the material is anything like their magazines. your going to have a fun time. I attempted to smooth up recent Korean imported 40s for the G22. They are not the drop free type, and they were a on the tight side loading and unloading. Steel wool (coarse) NOPE, file NOPE, nothing touched it and only slightly etched the high areas I attempted to bring down slightly, I decided not to try grinding, but I might try one with a Demeral some time. I would be really surprised if sandpaper worked. I have all four generations of Glocks along with a carry G 27. With my short fingered large hands, the 4th Generation is number one. It comes with the smallest back strap on it with two more larger sizes with the last one stock sized I guess. As is, a much better comfortable fit. It is textured like the 3.5 Generation, or RTF. Finger grooved ( Not quite as pronounced as the Gen 3 and 2), The 4 also has double slide return spring that like the sub compact, tames down recoil. A larger Mag. latch that is a real boon and doesn't require a shift in the grip to drop the Mag. If you ever hit the lottery, I was able to handle Lone Wolf's proto type lower handgrip, all I can say is wow!!! I installed a couple of their barrels a year ago to be able to safely use cast bullets for practice if I wanted to. Both worked perfectly and groups shrunk to half sized! There doesn't seem to be a lot of material in that front finger grip area, you may want to use some care if you find it workable.
