I compete in Benchrest Single Shot Matches with the longest shots being 300 yards. I currently shoot smokeless and am not interested in shooting black powder. The bullets must be plain base and I cast my own currently for 38-55 and 40-65. My 38-55 has a 12 twist so I shoot heavy bullets (360 gr). I shoot 400+gr in the 40-65. I am not shooting these fast, somewhere in the 1200-1250 range. We shoot from sticks with no rear bag. My question is if the sky is the limit what would be your optimum "rimmed" cartridge to shoot max 300 yards. It needs to shoot 2 moa or under at 300 yards. I am hoping there is something that is soft shooting and accurate to 300. I do not find shooting off the sticks to be easy and I'm hoping lighter recoil may lead to more consistent gun management. Been looking at the Schuetzen chamberings but since I believe they just shoot 200 yards I am thinking they may come up short for 300 yards. Thank you in advance for your thoughts and replies.