as i no longer own a Chrono (stray bullet from a 243 AI) I had to come up with a way of testing/ comparing loads, so what i did was make up a backing board and shoot both loads at the same point and walk backwards shooting a group every 50m. the piccy is the resulting target.
Groups circled in black are 140gn Partition's and the groups in pink are 129sst's. i shot the 140's first and then the 129's in order to get the 129's on the board i had to hold off the board to the right. don't pay to much attention to the size of the groups (that square is pretty small at 250m)
i think i'll go with the 129sst's as i've got 300 of them.