The tapered case of the 9X19 makes it incompatible with the rest of the 38/9 family. .380 cases would bulge if fired in a 9mm-compatible chamber. The grooves ahead of the rims are different in each case. The Super gets by with the same shellholder as the 9 but the case head is slimmer like the .380 - so the TK conversion to shoot 'everything' out of one chamber sounds great until you bulge the 38/357 cases and overwork them in the sizer die and shoot them with magnum loads in the hogged-out chamber again and get a split or annular separation. They can fly-cut your cylinder for clips, and provide the proper .380-size moons, so you can use .380 for a sub-cal without doing the 9X19 chamber cut. You can also use .38 Short Colt or .38 Long Colt for sub-cal shooting.