[Buffalobob]

So the first two jobs are to break in the barrel and find the top of the pressure curve for the chamber. I had four good powders for the 260 so I loaded up a series of five rounds with IMR 4350, Varget, RL17 and RL 22 (I wish I had a bottle of RL19) and some Berger 140 grain hybrids. For each powder, each round had a 0.5 grains more powder than the preceding one up to what I thought might be a max load the chamber will tolerate. This would allow me to find max pressure and velocity. I also had the bullets seated to jam so I could later back off the lands if I needed to.
During barrel break in, the rifle was cleaned frequently and it affected how the bullets flew being as I did not completely dry the barrel before firing. Varget is a good example of the barrel being cleaned midway through the string and how it opens up the group. In the other three powders, the first shot is always out of group due to cleaning. Even with the difference in powder charge, I thought RL17 was least sensitive to powder charge and I do not believe I reached max pressure with the loads so I will pursue finding an accurate load with it by gradually increasing the powder charge above where I left off.
I would just note that shooting an eight pound rifle accurately is a hell of a lot more difficult than the 14-18 pound rifles I normally shoot.

There are a few stray bullet holes from when I was getting the scope adjusted so you can ignore them.