I tumble before depriming because the tumbler media gets stuck in the primer pocket. You probably just had a hard primer. Some guns don't hit the primer as hard as others and every now an then you'll get a hard primer that doesn't light off. If it's a revolver, you can back it up and hit it again, which usually does it. I would just toss those cases. Getting the possibly live primer out could set it off.
I went to buy more powder yesterday and they were out of Accurate No.5, so I picked up some Clays. They said it burned cleaner and faster than No.5 and thus required less. I was using 8.1gr with No.5. Clays calls for 3.8. Half the powder means twice the round per pound.
It's easier if you just stick with one powder that way once you have your prefered loads figured out, you don't have to worry about it again. If you change powders, you have to go through the whole testing phase all over agin to figure out optimal loads for you guns. For 45ACP Clays calls for 3.7 - 4.0 grain. I'll load 20 each at 3.7, 3.8, 3.9 and 4.0 and test fire each. Optimal loads almost always end up being right in the middle. In my case, I expect 3.9 will be about right.