I'll be at the RBC and regular shoots coming up in Davilla this Feb-Mar. If anyone has a head space gauge for 308 Nato and are going to be at Davilla please let me know and I'll bring out my 308 to check it out. Been having lots of misfires in an FAL I just did some trading for and am thinking maybe I have excessive head space. Maybe?
The primers are getting what looks like a good hit from the firing pin but many rounds have failed to ignite.
Maybe it is just bad ammo but I tried two different batchs, which were old 70's mil surp, one batch with the hard primers, with about 30% failing to fire. Maybe worn out springs? I don't know much about this particular rifle. If anybody has any other suggestions I am all ears.
1 Check the "duds" by firing them in another .308 rifle to see if they go off. If not, it's the ammo.
2 I don't have the FAL down here to look at (and haven't looked at enough to remember the bolt lockup/setup) but if I wanted to check my M1 or M1A I'd remove the ejector, extractor and firing pin from the bolt, remove the recoil spring and drop a round in the chamber and ease the bolt home by hand "feeling" for how much effort it took to reach "lock up"
3 If it locked up easy I'd cut some paper shims the size of the bolt face and measure the shims with a set of calipers to determine the paper thickness in thousandths of an inch. Then I'd put a piece of paper on the base of the cartridge and again (pushing easy) close the bolt to lockup.
4 Repeat by increasing shims one at a time till the bolt won't easily lockup and multiply the number of shims it took to reach the "no go" point by the shim thickness to see how much "room" you have with that chamber and bolt.
5 Then repeat that exercise with a known "good" rifle to see what the difference is.
Not a definitive number, but a good comparison of a "working" rifle to the FAL that is giving you problems.
Now, folks who know more than me say that even if the rifle "eats" a .308 Winchester Field Gauge that doesn't mean its out of spec. for 7.62 NATO. They say a 7.62 NATO Field Gauge (when yrou can find one) is even longer than a .308 Winchester Field Gauge.
Good luck. Hope it's you ammo and not your rifle.
I had that happen. Removed the firing pin and cleaned/lubed the bolt interior. There was gunk on the pin. Since then, no problems.