Mauser Firing pin protrusion


Cosmoline is Evil
January 6, 2014, 10:11 PM
Hi All

Can anyone tell me what the correct firing pin protrusion specs on a M24/52c are? What is the preferred method for measurement


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January 6, 2014, 10:17 PM
.035"-.060" is normal. Measure with the depth rod on your calipers.

Jim K
January 6, 2014, 10:30 PM
Spec is .055" to .065", but split the difference at .060"; there are special gauges, but you can check it with a caliper. Just make sure that the firing pin doesn't protrude when the firing pin is cocked, as closing the bolt could fire the primer with the bolt unlocked.

(FWIW, firing pin protrusion does not cause pierced primers unless the firing pin is actually sharpened to a point. So-called "pierced" primers are the result of a weak firing pin spring that allows pressure in the primer to drive the firing pin back and force primer metal into the firing pin hole.)


January 7, 2014, 12:37 AM
I recomend using a firing pin gage tool like JimK mentioned.
I see guys try to use just a dial caliper, and they get incorrect readings, especially when they can not put forward pressure on the firing pin, to check for any slop on the parts like the cocking piece to firing pin keys.
I look at it this way.
If it wasn't a critical dimention, then why would someone make and sell a tool designed especially for checking that dimemtion.

Jim K
January 7, 2014, 04:22 PM
It is a critical dimension for several reasons, but there is a fair amount of leeway.

Obviously, a firing pin that doesn't protrude enough will result in misfires. One that protrudes too much will get in the way of the cartridge when feeding from the magazine and jam the rifle. And then if the round does ride up the bolt face, or a round is fed singly, chambering it with a protruding firing pin can set off the primer before the bolt is locked, with no real good result.

So a firing pin that will protrude too much only when the bolt is closed and locked is unlikely. There are many warnings that a excessive firing pin protrusion or an over-strength firing pin spring will cause "pierced" primers, but that is not true. The oddity is that "pierced" primers result from a too weak spring or a too light firing pin; but often folks who experience that condition take bad advice and weaken the spring further, which results in more primer "piercing", so they weaken the spring more, with more "piercing", until the gun doesn't fire.

FWIW, I have deliberately used a firing pin with a very long nose and struck it with a hammer to drive it into the primer. I could never get it to "pierce" a primer or the primer metal even when it crushed the anvil.


January 8, 2014, 10:50 AM
Any T.S.J.C. graduates out there? There was a time when a very useful "Protrusion Gauge" was part of the shop project booklet.
Lots of good stuff in that project booket.

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