i have a 416 rigby necked down to 7mm shoots up to 3600. but mine is most accuate at 3500 to 3540 with the 160accu bonds. mine gun was built back in the 70s by a gun smith out of greatfalls mt. he was on the same track as the allen mags back then. i have a couple of versions of this design 308 and a 375 but i still shot the 7mm to honor my grandfather who designed then. they are full lenght cases necked down and blowen out side walls with a step shoulder. they are built on pre ww2 rigby and pre 64 win actions and 30in barrels. when he built them the powders were limited and preformance was not there but with the new stuff out there things have turned around and with the new brass available to use i can work up to higher and better performance out of them.
not trying to bash your G7 number and i dont have any personnel experience shooting the 160 accubond at long range so i basically have no real world experience but .310 seems high to me. berger 168 is .318. I am going to try your number tomorrow and see if it works. But if it works for you thats all that matters.