kingzero, I know all rifles are different and like different things, but my 260 loves 43grns of IMR4350, 140grn PSP,CCI BR Pri. Hodgedon lists only a max load for this at 43grns, 2715fps, and only 57,000psi, so I went with it right off. No pressure signs. This combo shoots bug holes at 100yds and 1/2 Moa out to 300yds for me. I could easily be wrong, but I doubt your issues are coming from the IMR4350. Off hand, I suspect your not using enough of it. O yes, the 140grn PSP is a "bore ryder" bullet, and this makes it easy for me to start it "touching" the lands, which I think helps this combo. Good Luck-Good Shooting........Jim