One of the big problems I find crimping any wadcutter flush or slightly below is when the brass rolls over the bullet it has a tendency to force the bullet deeper in the case and cause seating depth variations(causing velocity variations..). With mixed brass this will be more pronounced. I like to seat my wadcutters just a hair above the case, it eliminates the issue. Also a good firm crimp is hard to acheive, it always seemed like a good solid crimp has helped with accuracy regardless of the caliber. I realize 52s are supposed to be seated flush, but give it a try, rested @ ten yards you should be getting sub-inch groups from that pistol fairly easily..