Try the Speer 250gr GDJHP in .45 Colt. It'll make ~800 fps from that 4" tube - great thin skin stopper. Reported frontal diameter of .76"+ and little mass lost - good penetration, too. A 255gr LSWC at the same velocity or so is effective, too. In my loads, I can get 850+ fps in standard pressure loads with those bullets - some folks load to over 900 fps for their 625 MGs. The Speer 250gr Gold Dot, #4484, is pre-stressed/thin-walled for low speed enlargement.

I have two 625MGs - super fun. ongratulations - the 25MGs are beautiful.

Stainz