I've never had any bullets on the .750 jacket but have shot a few 1000 made on the .790 and a whole bunch more made on the .825 jacket and the 14tw has been my go to barrel, I tried a 13.5 and a gain twist and they didn't seem to shoot any better than the 14tw.I have made bullets on Hines jackets. They shot very well. I wish they would make a run of .750" jackets. Up here in the NW several of us really liked the J-4 .750" jkts that are no longer available. A 64 gr. bullet on a .750" is perfect in a 14" twist. Since most short range bullets are now made on a either a .790" to .825" jackets, may explain why most shooters are using either 13.5" or 13.0" twist barrels. Longer bullet spin it faster!
FWIW
Steve Kostanich