Don't do it. Had one on a LEO Glock 23 I carried.. After about 2000 rounds through the gun, I got Type IV after Type IV mal. I threw the Harts gimmick thing over the berm (er, uh, placed it nicely in the trash bin at TR) put the stock spring back in and it worked like it was suppossed to (until the slide stop spring broke).
Lessons learned: 1. All guns break. 2. Get more guns. 3. Have plenty of parts on hand. 4. Who knows more about Glocks--you or Gaston Glock?