I don't want to get into your little "DISCUSSION" but I don't think I've ever seen a 375 bore rifle with anything but a 1-12" twist. That, however, doesn't mean they don't exist. My 375JDJ VALMET 412 was re-chambered from a 375Win Mag, to 375JDJ, and the barrels were 1-12", and all three of my Mauser rifles are 1-12" twist. They all shoot very well,but I only use 300 gr bullets in 375s.