Thanks. I used Win brass, CCI#200 primers, 175gr SMK, seated to be .010 off the lands, 44gr Varget. Chronograph results 2710fps. I felt no bolt tightness until I fired loads with 45gr Varget. Groups were low and stayed there starting with 44.2gr Varget. In a previous work up with Win brass I thought I had found a load at 43.6gr Varget. When fired at 300yds, they grouped 6 inches. A three shot group with 44gr Varget at 300 yds grouped at .8 inches. Covered the holes with a nickel. I started at 43.6gr Varget and worked up because I know that the Win brass has 2gr larger internal volume than all the other brass that I measured. My most accurate load with LC brass is 43.2gr Varget. But LC brass has a 2gr smaller internal volume. The speed on that load is 2665. Let me know what you think. Obviously, I can back off on the Varget and try to find another node. I use a shell holder at the range and check each empty case for fit after it's fired. I noticed no difference until I reached 45gr Varget. There was a very slight snugness at that point. Clearly with that info and bolt tightness, 45gr is too much. I always check loaded cartridges with a Lyman head space gauge. If the cartridge doesn't fall in and out, I don't fire it.