I've wrecked cases by not paying attention when resizing, broken and bent decap pins and rods.
I've crunched cases when hitting the crimp ring in seating dies.
I've forgot to check if a partial resized case would chamber, had rounds in a batch that were set up tight, that some would not chamber later.
Had bullets that had to be sized more after springback, and would not chamber without semi breech seating.
had a few no powder pouts, and some that actually were primer issues
had a couple of partial charges from powder bridging, and a few that broke loose and overfilled the next one.
Collapsed cases from low charges, pierced primers from hot ones.
had a batch of primers that hang fired at a match shoot, they were loaded right there, at the bench
broken bullet sizer linkage
wrong sized expander in a new die
brass splitting in an egged chamber
a batch of recalled powder, locking up a gun on a starting load charge.
broke the shellholder section off Lee primer tools three times, had two handles break
seated primers sideways, and upside down
slightly overheated bullets in the oven.
moulds that would not make size, and were oversize