I did some experimentation recently with standard flat-ended wadcutters shot into dry catalogs (probably not realistic material, but it's all I had). The ones in front are 148 gr. .38 specials, in the back are 225 gr. .45 ACPs. Unlike some jacketed and hollowpoint bullets, none of these came apart, and some of them expanded quite nicely. The .45 at the back left is more than .75" at its widest point.
Edit - I should note that these are target-loaded wadcutters. I use either 3.0 grains of Titegroup or 2.8 gr. of Bullseye for the .38 specials. For the .45 ACP rounds I use 3.5 gr. of Bullseye.