I'm back into reloading after a long time away. I started on a single stage RCBS back in the 70's and I loaded tens of thousands of rounds, one by one.
I'm now using a Dillon 550B (having loaded about 1000 rounds so far) without any issues BUT . . .
Today I took out some .40 S&W that I'd loaded. These rounds were loaded with 180 grain SNS LRN. CCI primers.
I had two "misfires". I was very unhappy (with myself).
After looking at the two misfires, I found what I think were two light primer strikes. I had two failure to fires out of the 100 "test" rounds I'd loaded.
First time I'd ever had a misfire - ever.
I checked the two rounds. The primers on both of them had slight dents on them.
I reloaded the rounds and they fired perfectly.
In retrospect, I think I didn't seat the primers deep enough in the primer pockets.
I blame myself for not seating the primers deep enough but I thought I'd "finger" checked the primers to make sure they were all seated.
No question - my error on the loading but I'm going to learn from my mistakes.
Of course, I've got some more .40 to shoot and I'm going to check the seated primers. If I found any that look "high" I'm going to mark them with a Sharpie and see if these "misfire".