I had to get out to the range today to shoot a new Mossberg 590A1 14" SBS that I had bought for the PD I work for (I'm the head firearms instructor and in charge of all firearms/ammunition procurement). If interested, the review of the shotgun is in the shotgun subforum. The shotgun part of the range day went well, then I took the opportunity to shoot the personally owned 9mm M&P 2.0 that I'm using as my duty gun. Before today, I was up to about 2000 rds through the M&P.
I had run a couple of magazines through the pistol without a problem, then it started on the 3rd magazine. A light primer strike about halfway through the magazine. I was using my reloads, so I didn't think much about it. I've never had primer issues with my reloads since I started reloading 30 years ago, but shit happens. The next magazine, 2 more light strikes, so I did some investigating.
First off, I stripped the pistol, pushed in the striker safety and pushed the striker all the way forward. Truthfully, I was half expecting a chipped or broken striker nose. Nope, nice and round and smooth, with more than sufficient protrusion from the breech face. I then pulled the striker from the slide and found the problem. Quite a bit of brass shavings and general schmutz and thick oil on the striker and in the striker channel on the slide. I thought about and I've never pulled the striker to clean it, and I don't remember cleaning it out when new, either, so it likely also had preservative shipping oil in it. Cleaned out the channel with a q-tip and wiped the striker assembly down with an oily rag, put it back in and tried it again. Just like that, back to normal, flawless operation. Just to make sure the issue was solved, I fired 6 more magazines. Reliable function, so I'm calling the issue solved.
Moral of the story- provided you know how, remove the striker/firing pin once in a while and clean it out. It's not hard to do at all on most guns. If you do like I do and wipe the breech face down with a patch wet with solvent as part of cleaning, the solvent can get into the striker/firing pin channel, attract schmutz and debris and cause an issue. Just make sure that you DO NOT oil the striker/firing pin or the channel, reassemble it dry to keep from attracting the schmutz in the first place.