The several hundred rounds that I loaded were done using a load that I had tested in 10 rounds that were fired the previous day at the range. When I try a new load I only load at most 10 rounds to test. Then if I like the round I will load several hundred to shoot over that weekend.
The high primers where caught at the reloading bench but there where a couple that I was thinking would still work in the gun. Those I took along with me to the range to see if they would work but they did not.