Recently purchased a Mod 64 3 inch heavy barrel. When shooting at 10 yards the bullets keyhole. Loading 4 gr 231 with a 125 gr Berry plated bullet. No problems with this load in any other revolver.
Any suggestions?
Make sure those plated bullets aren't .355" or .356" !
A fellow reloader purchased a box of plated , they were supposed to be for 38 spcl. but they were sized .355" and didn't shoot for Heck or High Water . Poor accuracy .
Would hit the target sideways sometimes .
I think they were supposed to be 9mm Luger bullets and got packaged in the wrong box. I couldn't make them shoot in his 38 spcl.
Too small is just about useless .
Gary
Another possible cause could be a forcing cone that's too small or barrel constriction where the barrel goes through the frame.
Compare with some factory 158 gr. ammo.