Technical: Firing Pin dent on primer when bolt closes?

[Charmedlyfe]

I noticed a tendency of my FAL to leave a small dimple in the primer of rounds chambered (ejected without firing) I traced it to the 1-piece pin. I had replaced the spring 4 times in an attempt to correct it. I got one of the 2-piece Israeli firing pins from DSA, and had no further problem. This concerns me in that I might have had an ND when I hit the bolt release. If you haven't checked for this and you've got a 1-piece pin, PLEASE CHECK IT! This has also shown up in a few weapons coming into a friend's shop.

[ July 24, 2001: Message edited by: gary.jeter ]

[W.E.G.]

The condition you describe is completely NORMAL. The same condition occurs with every M16/AR15 I have ever seen...which is quite a few.

If you slam the bolt on a live round, then extract it without firing, you can be certain there will be evidence of contact from the firing pin.

[Ape]

This is also normal with a M1 Rifle. This is called firing pin slap. Where ya get into trouble is having too much firing pin protrusion, long cartridge headspace and a shallow primer pocket. Add that all together and guess what. SLAM FIRE! That is why many of the professional builders do not recommend re-loading for these calibers in a semi-auto. I have for years, but I uniform the primer pockets, re-size correctly and measure accurately.

Hope this helps

[Arby]

Gary & Ape,

Thanks for the posts on this subject. As is often the case, one person asks the question, others have had it for years and never asked.

My favorite and most accurate Garand does this with reloads, and I have been careful with it for a long time, afraid it would slam-fire on me. This could be a real drag, especially with the climb one would experience with a full 8-round clip (the AR does it too, with reloads, but 5.56 is controllable). I feel better now, though I will still take the usual precautions. Thanks again for the info.

[This message has been edited by Arby (edited February 11, 2001).]

[Mr pogo]

AFAIK all metric FPs are one piece. Commonwealth Fals were changed to 2 piece in early 60s to stop slamfires but FN never adopted change. However, Israel did redesign some of their Fal parts to their own design, possible they came out with a 2 piece. I have to call DSA this week to order some stuff, will ask them about it.

Arby, checkest thy firing pin on thy M1. The FP has a leg that catches the receiver bridge before bolt locks up, either FP or receiver could be out of spec due to wear. Remove receiver and flip it over, close bolt slowly and watch FP as bolt closes. Wear (or out of spec parts) can let FP protrude too much.

[kev]

Add the AK and SKS to the list of guns that will dent the primer on firing. (Oops, how about dent the primer on chambering,....all guns dent the primer on firing) I think the Poly Tech Legend series is the only AK with a sprung pin(caution: old info. May not be valid anymore). It's not a problem with hard milspec primers, but can be with commercial caps. CCI makes a hardened primer specifically for reloading ammo for the military self-shuckers.

[This message has been edited by kev (edited February 12, 2001).]

[Charmedlyfe]

Whatever. None of my ARs dimple the primer. The israeli pin fixes the problem in the FAL, so I'm not worried. just one less problem to worry about. And this was NOT on re-loads....

[JohnnyMac]

Some of the SKS rifles DO have spring-loaded firing pins. There was a problem with slam-fires* on SKS rifles from China. The apparent culprit was a heavy layer of dried cosmoline that "glued" the firing pin in the forward position in the bolt. This was correctable by properly cleaning the bolt and FP. The spring mod was done to lessen potential liability for the importers.

JMc

One of those fly-by-might books that claimed to show how to make an SKS full-auto, simply showed how to use a piece of heavy wire to pin the FP in the full forward position.

[CC]

Not only legends, but every Poly Tech AK I have ever seen including the latest ones have had the spring type firing pins...CC

[Mr pogo]

Talked to Jeff at DSA today when I ordered some stuff. He said the Izzies were originally 1 piece, they went to 2 piece to prevent FP breakage. Sooooo, Izzies once again another unique variation http://www.fnfal.com/forums/wink.gif

I checked my Izzy HB FP, its 2 piece (dont know why I didnt pickup on that when I first got it), leaves a shallow dimple on primer of RG. But FP impact when fired alot deeper, not too worried about leetle dimple, noway internal primer parts can come together for firing.

[Ape]

That is why you should never chamber a round not stripped from a mag. Slows the bolt down enough to minimize the fring pins inertia. I know this is the Fal Files but I love my garand. Check out the book US .30 cal. service rifles a shop manual by Kuhnhausen for a picture showing 7 examples of dimpling from good to strap it to a tree. Of course this also applies to the .308 to which I was heading. The chapter pertaining to things to be aware of reloading this round for a semi-auto is worth the price alone.

Arby
Mr Pogo is correct. check that FP tang shoulder. It should show a crisp/sharp corner. As it wears it will round thus increasing FP protrusion.

[This message has been edited by Ape (edited February 12, 2001).]

[This message has been edited by Ape (edited February 12, 2001).]