This thread reminds me of the first few times I took my M48A out with 50's ammunition (154gr cupro nickel flatbase FMJ loaded by FN). I cursed the rifle as I kept getting light primer strikes. As the rifle warmed up, it would begin to work reliably so I knew it wasn't the ammo. I was at the time suspecting a weak spring.
Turns out, I hadn't removed all the cosmoline inside the bolt and only after the heat had affected the viscosity did the pin have enough velocity to impart enough of a strike for reliable ignition. I had taken the advise of a buddy to soak the bolt in fuel to remove the gunk. In the end, I simply took the darn thing apart as I should have on the first place and removed a good deal of grease. The rifle was flawless ever after.
BTW, the 50's fodder I bought for $70/800 has 50 and 51 headstamps and is Berdan primed/Corrosive. I scooped up 1600 at the time and have run through about half of it.
The bore is still mirror bright as it's been cleaned the same way as with my other firearms that see corrosive surplus ammo, 3 or 4 soaked cotton patches (with whatever glass cleaner is on sale, usually something generic) down the barrel first, followed by a couple dry patches and then cleaned as usual with Break-Free or again, whatever is on sale that's similar. I save the hot soapy water fiasco for my black powder firearms.
BTW, the ammo I wrote about dried up in 2000 or so... But if you run across the old FN stuff (Belgian?) packaged 100 to a (disintegrating) box, I'll vouch for them as being surefire and reasonably accurate presuming they were stored as mine were.
