AK misfire problem?

[fatelk]

My friend and I were shooting his AK rifle, and I can't figure out what the problem could be. I know many of you will laugh and just say not to shoot that junky old ammo, but here's the thing:

We have a bunch of questionable old Egyptian ammo. I think the primers are on the edge, kind of like the 50's Yugo 8mm. In my rifle (Romanian) at least 90% of it goes off, with the occasional dud. In his (Polish "kit gun") at least 90% misfires.

We checked the firing pin protrusion, hammer spring, and headspace. Everything seems to be fine, virtually the same on both rifles.

Yes, it does work fine with modern ammo, so we can just shoot up the old junk through the rifle it works in, but I am curious as to what the difference could be.

Any ideas?

 

[dfariswheel]

The ammo made by Egypt was noted for hard primers.
This was in both rifle and pistol ammo.

Second, it's not unusual to see an AK in which the hammer spring has been straightened enough to give light strikes that will fire most ammo, but not something like your Egyptian stuff.

If it's firing newer ammo well, just make do with the Egyptian ammo. If not, try giving a more downward curve to the "legs" of the hammer spring to increase tension.

 

[bigbob76]

Swap out the hammer springs and see what happens?

 

[fatelk]

It turned out to be the firing pin after all. I sure couldn't see any difference between the two pins from the two rifles, but we swapped them and it shoots the Egyptian ammo now with very few misfires. Now we just need to order a new firing pin.

Thanks for the suggestions. We actually did try that before trying the firing pins.