My 26in 6br with 109 Bergers shoots amazingly at 2760 and 2810 w/ N150, 2810 is a lil hard in brass, so I backed it off a bit. Everyone wanting to go 6arc, opening and bushing bolts, idk why, the 6br is THE perfect low capacity 6MM.I was more concerned about the lack of velocity with the heavier weight bullets
I was playing with the 6BR in the early 70's. Its was brought about mostly by Jim Stykle at Remington Arms when they were building 40X BR guns. 1 in 14 was the twist rate.