As an aside, with a very light recoil spring combined with hot loads are you not going to be battering the ever-loving bejeezuz out of the frame?
I'd be against using anyone else's "+p+" recipes as well - too many variables. How much over recommended specs are you already? Tried steadily increasing charge? Or tried faster (or possibly slower) powder? Magnum primers?
Not advocating any of the above as good ideas - just brainstorming
"The best diplomat I know is a fully charged phaser bank" - Montgomery Scott