I'm running 78gr of imr 7977 at 3.390" coal which is as long as they will go in the magazine. Not even close to the lands with the .378" freebore on the mkv. It's a 10 twist and I hunt at less than 1000ft asl.
I've had petals come unglued on a 100gr ttsx in the 257 bee, which I see as a good thing. They act like the cutting edge bullets then which I don't mind at all.
I think I will run the 127 lrx.
