I thought I had found my magic load for my 7 SAUM using 180 Bergers and H-1000. I shot 3 rounds that measured .54" @ 300 yds with only 7 fps spread. I loaded 15 more exactly the same as the 3 and shot them a week later when the weather cooperated. I shot all 15, with a few minutes between each, in the same conditions as the 1st 3. This time the spread was 46 fps and only half of them were within the original 7 fps zone. The barrel was not heating up and the velocity varied up and down as I shot. The group measured about 1" L-R and about 2 1/4" vertical. This is the second time the same situation has happened. I am detailed in my brass prep and reloading but not sure if I am doing something wrong. Does anyone have any ideas? My barrel is 28" with a 1-8.5 twist, which is plenty for the 180's. I weigh each charge with a RCBS Range Master 750 Digital Scale and check the zero after each charge. I let it warm up for at least 10 minutes before each use. I use power measure to get close and a trickler and put in one grain of powder at a time until the # I need just turns on the scale. I'm using CCI BR-2 primers and hand seat them. I use a Beta Master Chrony and it is set up at the same distance each time. I have eliminated as many variables that I know of. Am I missing something? Thanks in advance for any advise.