I am shooting Lee 358-125-RF cast in my Sig 9MM. They drop at about 0.361" and I size them to 0.358". I seem to have a nice load and no leading at 3.7 grains of Unique. I having been wanting to slug the Sig barrel just to have the data. Thought it might be possible to retrieve a fired boolits from a sand trap and get some data. I fired 5 rounds into a fine "play sand" trap at 25 yards. I got great expansion that was all slightly greater than 0.5". The bases of the boolits looked to be undisturbed. I measured the base of the boolits and they ran from 0.353-0.354". Is is possible the barrel diameter is that small or is something else going on that I do not understand.