I am having problems with keyholing out of my 10mm practice load. I use a Dillon 550B. It is a 180 grain TMJ with 7.7 grains of unique at an OAL of 1.25. It has worked great until recently. I think the problem is with the amount of bell on the case. I had a batch with quite a few keyholing rounds, so I checked my set up and added a little more bell at the second station.
I loaded 25 rounds yesterday, and it seemed like the amount of bell decreased with each successive round (though I made sure the die was snug). Today I went and shot them and only got 2 keyholes out of 25. This makes me think I may have solved the problem until the die "slipped". Does it seem like I am on the right track with this problem, or should I be looking at the amount of crimp (which was based on Dillon instructions)? I had considered that as an alternative source of the problem.
I loaded 25 rounds yesterday, and it seemed like the amount of bell decreased with each successive round (though I made sure the die was snug). Today I went and shot them and only got 2 keyholes out of 25. This makes me think I may have solved the problem until the die "slipped". Does it seem like I am on the right track with this problem, or should I be looking at the amount of crimp (which was based on Dillon instructions)? I had considered that as an alternative source of the problem.