so on the night of the "blood" supermoon eclipse, i went out and shot a bunch with the NV and my suppressed noveske SBR lo pro switchblock. at the very end, I fired what felt like the last round and as usual, cleared the weapon by dropping the mag and cycling the charging handle twice and locked the bolt back, then put the gun on the stand for the suppressor to cool for a while, then I threw it in the truck where it rode for a few days, then put it on the stand at home day before yesterday.
Last night, as I walked by its stand at home, i noticed the bolt was slightly out of battery. so I opened it up and was very surprised to see a round in the chamber, which had no primer, so i assumed it was spent. So i cycled the charging handle and it didn't come out. on closer inspection, I realized the missing primer was laying, not stuck, just laying, on the face of the bolt, which was hitting the back of the case and preventing the bolt from going into battery. simply turning the gun up and shaking it slightly caused the primer to fall out into my hand. then the bolt closed normally and extracted the round which turned out to be live, minus the primer of course. I did have to pogo it slightly because the case had corroded into the chamber a bit.
http://precisionmultigun.com/pics/supermoon15malf.jpg
There are still a couple of unsolved mysteries here, but basically, the last round in that mag went into the chamber, but the primer which must have been very loose (these are reloads with brass with unknown number of firings) somehow came out early enough to prevent the bolt from going into battery. I was running and shooting on uneven ground at the time, so I'm not super surprised that what felt like the last round and a bolt hold open caused me to stop shooting, but was really neither.
the fact that the bolt wouldn't go into battery meant that the extractor never got close to the web despite multiple cycles of the CH which felt normal. and since it was dark, I couldn't see that the bolt wasn't going into battery.
i guess i learned that I can't really feel the difference between the bolt going into battery vs almost going into battery when cycling the CH.
What's a little different about this, was simply that it happened on the very last round I fired for the weekend. If it had been in the middle, I would have done immediate/remedial action and fixed it. instead, i went a couple days before I even discovered it.
I don't keep exact records of malfunctions anymore, but I'd guess I'm averaging maybe 1-2 ammo-related malfunctions (and near 0 non-ammo related malfunctions) per 1000 rounds of these reloads. I've got a bit over 7000 rounds on the gun now. For the roughly 17 cents ($170/k) it costs to reload with a 75g bullet, I can live with this level of reliability for practice ammo.
and it's another good reminder that all guns are always loaded, even when you think you just unloaded them. especially in the dark.
if I'd needed to use the rifle since sunday night, i would have been screwed. and i need to clean a bit of corrosion out of the chamber.