I'd guess part of it could be attributed to lead core 110's being a 1/4 mile from the lands.
In a tight chamber, jumping may not be so bad. Look at Weatherby's that shoot very tight groups with long freebore. I'm working with a 26 Nos and it seems the more I jump some bullets, the better they shoot.
I just got a couple of boxes of Barnes 110 gr. TAC-XT for the .300 Whisper. I may try some in my .308 to see what they'll do.
DF
