i'm gona hafta spike my reloads up or something cuz i have a remington model 7 with a 20" barrel and im only getting 2850fps and ur getting 2875 out of a 18.5 sounds like im gona hafta experiment. I may cancel that idea though the 2850 seems just about the right speed with the 95gr nosler ballistic tips outa the cartridge. I feel the 6mm rem is one of the most underrated cartridges on the market. If they just woulda had the twist rate right when the introduced it as a 244. im sure it would've outshined the 243. I've used both and talked to people who have used both even though they both shoot the same bullet everyone i've talked to has had better preformance with the 6mm they said they haven't nor have i seen any cripples on good shots with the 6mm. But i had 2 bad experiences with the 243 both on around 120lb whitetail does. both resulted in dead deer but it required extreme effort on my part even with good lung shots. It wasn't bad bullet construction either i shot one with a 100gr sierra semi point, and another with a 100grremington core lokt.The 6mm to me just seems to have a little more punch to do the job a little better. I had a 243 bullet lodge in the shoulder on a quartering away doe from about 150yd it was very slightly quartering away and the bullet didn't strike any bones and it lodged in the meat in the inside of the far shoulder. It resulted in a dead deer but not near the preformance i wanted. I've shot a wild boar and a whitetail doe and buck all through the shoulders with a 6mm remington and penetration is no issue what so ever my slug always exits the animal causing a massive wound and making recovery very very easy. Both guns are good deer size calibers in my opinion with proper shot placement, but if given the option im going to take the 6mm rem over the 243 any day.