Since the thread from a couple of years back I have been itching to try it. So I finally did. The Numrich underhammer I have has a massive barrel on it with wall thicknesses twice what any other gun I have is, so I picked it as the weapon to use. I loaded it with my usual 80gr load of 2f and sent a patched .575 ball down the tube, followed by a second patched .575 ball. Capped it, took aim (at 50 yards) and let her go..... Recoil was about the same as a TC conical, not too bad but definitely more than a normal round ball load. To my surprise, accuracy was not too bad either. One of the balls hit about an inch low and the other off to the right about 2" Felt good so I repeated the load and fired again. Four holes within the 3" ring around the X. All in all, not too bad of a pattern. Anyone ever try three?