My experience with bad primers has been very low. With “fresh” primers that have failed I cannot think of an occasion that the primer itself was defective. Improper seating that damaged the priming pellet or defective firearms have been the cause. I’ve had one factory round fail to fire, a Federal 9mm. The case had no flash hole! Several years ago a friend bought a large lot of reloading equipment and supplies from an estate. Included were primers from the 1950’s if not earlier. They included Remington, Winchester, Federal, Western, and CCI. All but the CCI and some of the Remingtons were the old domed style. All were large rifle type.
There were about 27,000 primers and my friend didn’t want to use them because he feared some might be corrosive and he didn’t want to figure out how to seat the domed ones. All the 100 primer cartons were marked as being non-corrosive in one way or another. He wanted to dispose of them safely. I suggested he could put them in my pickup and I’d destroy them (one at a time). From the condition of the cartons these primers had not been carefully stored; sun fading, water stains, and mystery stains that looked like mildew. Most of the primers were not plated and the cups ranged from very bright and brassy colored, to dark, to having black stains and/or spots of green verdigris. Five minutes in the lathe modified an RCBS priming punch to seat the domed primers.
I just finished the last of these primers and was surprised that I had one failure to fire with the Federal primers out of every 200. There were just under 4,000 of these primers, all the same lot. About half the “bad” primers fired on the second try. There were a fair number of hang fires with the Federal which really re-enforced the need to follow through. All the loads fired were in light cast bullet loads and there was vertical stringing with certain lots of all the primers indicating they were not aging that well. One Remington and one CCI primer failed to fire, but went bang on the second try. I’m very impressed that 70 year old or older primers worked that well, especially with the obvious poor storage. My friend also found several old glass baby food jars of various unidentified
primers in this lot. At that time I was unwilling to experiment with these. We filled the jars with used motor oil and they were later placed in the trash. Under present conditions I wish I had taken these too, but then I think of the two times tubes of Federal small pistol primers have detonated in my Dillon 1000. Wow, thankfully Dillons outer tube protected me and sent everything through the ceiling. Also taught me to wear earplugs and safety glasses when reloading. A hundred or so primers sympathetically detonating is loud and impressive.