to the front of the bottom of the magwell. Extension spring, horseshoe shaped catch, wiht the engaging part going into the front-bottom of the mag. that will allow the hand to move up nearly 3/8" on the butt. Without a ducktail tang, tho, might not want to risk doing that. Have to see how it handles to know for sure. With a PPK type extention on the front bottom of the mag, and a Detonics slash of the top rear of the slide,and hammer-down carry, might actually be able to pocket a 1911 after all.