Oversize Firing Pin Damage

[Kiwi Mark]

Most of you will know this, but a reminder wake up.
Shooter Lugers. Too long a firing pin will piece the primer and if it doesn't have post 1933 gas by pass cuts, on firing the high pressure blows the firing back as it has a seal. This compresses the firing spring, blows the firing pin retainer out the back of the breach block. Very Sad.
A friend did this and when mine wouldn't fire after the 2nd shot, I picked up the brass and knew what the problem was.
OK, remove blue, a spot of weld, then dress it up with the Dremel,
All my shooter have these 3 gas by passes cuts in them. Not hard to do.
Prior to this happen, I expected that there would be so much pressure, it would blow the sear bar out and do some really bad damage.

[Mac Cat]

I don't know much about firing pins - which kind are too long ?
(I don't shoot a lot, but the few times I had pierced primers was more about the reloads than the gun....curious)

[Kiwi Mark]

Even with factory ammo, if the firing pin sticks too far out from the breach block face it can piece the primer, that goes with any firearm. Lucky for me it was a 9mm and didn't cause too much damage, but a 308W may have been a different story.

[ithacaartist]

I've never heard of a firing pin tip that grew like Pinocchio's nose before. If it sticks out too far, something is significantly worn, either the inside of the breech block where the striker bottoms out, or the striker itself. I remember seeing a post about a piece of factory gauging that measured F.P. stick-out. It was basically a precisely cut notch on the end of the tool, and a piece of a credit card filed out just as precisely was deemed an adequate substitute. Somewhere here at Luger U., there is a spec for this notch, i.e. the precise distance the tip of the F.P. was designed to protrude. If it's excessive, you'll dress the tip to gain the correct dimension?

[kurusu]

Luger firing pins don't tend to be too long. It can happen of course but it's not common. The pierced primers, in a Luger, generally occur from excessive headspace.

Either from out of specs ammo, more common on the .30 Luger even with factory loads, or from a mismatched breech block that wasn't properly fitted to the gun.

[rhuff]

Perhaps I have misread Kiwi Mark's post, but I interpreted it that he found that he had too short of a firing pin in his shooter Luger(misfire X2), so he built up the tip of his firing pin with weld and then dressed it down with a Dremel tool......obviously leaving it too long, producing pierced primers when fired.

[Kiwi Mark]

Sorry, I'll explain. It's a 9mm, a very tired old lady, 1917 DWM and dressed up with some good looking grips. So off for a shoot, nothing done to the firing pin. Aftermarket mag. After 2 shots, it failed to fire the 3th. Picked up the fired brass, and I could see the pieced primers and could suck air through the case. As well as protuding too much, the diameter of the tip of the firing pin is 1.3mm. The spot of weld was added to the rear of the breach block where the firing pin retainer clicks back in it's final position as it had blow the very thin bit of metal out.
Luger manufactures started to do the gas blow back mod on the front face of the firing pin from 1933, 3 slots. Was it for this reason??

[kurusu]

Most probably. I only use Mausers as shooters.

[DonVoigt]

Originally Posted by Kiwi Mark

Sorry, I'll explain. It's a 9mm, a very tired old lady, 1917 DWM and dressed up with some good looking grips. So off for a shoot, nothing done to the firing pin. Aftermarket mag. After 2 shots, it failed to fire the 3th. Picked up the fired brass, and I could see the pieced primers and could suck air through the case. As well as protuding too much, the diameter of the tip of the firing pin is 1.3mm. The spot of weld was added to the rear of the breach block where the firing pin retainer clicks back in it's final position as it had blow the very thin bit of metal out.
Luger manufactures started to do the gas blow back mod on the front face of the firing pin from 1933, 3 slots. Was it for this reason??

Actually the fluting started earlier, about 1930.
Its stated purpose was to improve striker performance in case of buildup of dirt/oil/powder residue; no mention of gas bypass.

Many think gas by pass is the "reason" for the flutes, see the recent discussion here:
http://luger.gunboards.com/showthrea...ighlight=flute

The surest way to improve gas bypass is to drill a hole in the bottom of the breech block, just aft of the spot where the striker stops against the inside of the breech- this is what the Norwegians and others did fora gas bypass.

Better yet is PM, inspection and correction of a sharp or too long striker nose(firing pin).

[DonVoigt]

Here is what the gage looks like.
An original Kreighoff accepted gage, and one of my home made ones.

The min and max are in mm.

Thus the end of the striker(firing pin) should extend at least 1.1mm past the breech block face, and no more than 1.35mm.

[stg44fan]

I believe this is the pic you guys are thinking of. From my understanding the hole is present on all Finnish Lugers just in case of a pierced primer.

[DonVoigt]

Originally Posted by stg44fan

I believe this is the pic you guys are thinking of. From my understanding the hole is present on all Finnish Lugers just in case of a pierced primer.

Yes,
that is it. Thanks for posting the picture!

[chr]

Thanks to all.
I am thinking now to update my shooting Luger with this hole.

Gold idea or not, what would you say?

[DonVoigt]

Can't do any harm, as long as it is a "shooter".

[chr]

Thank you!

[Kiwi Mark]

Hi, Thanks for for the info. My problem was. 032 excessive headspace. Once I removed the extractor and firing pin i could use a feeler Guage behind a sized case to measure. Machined up a new barrel out of a piece of barrel blank. Thanks to everyone for the help.

[Eugen]

Great information shared. This needs to be edited and incorporated into the FAQ section. Hats off to all the contributors.

[DonVoigt]

Originally Posted by Kiwi Mark

Hi, Thanks for for the info. My problem was. 032 excessive headspace. Once I removed the extractor and firing pin i could use a feeler Guage behind a sized case to measure. Machined up a new barrel out of a piece of barrel blank. Thanks to everyone for the help.

That is indeed a lot of "extra" space.
Thanks for reporting the "rest of the story".

[Rick W.]

You are indeed fortunate to have welding skills and barreling skills. Makes life easier at time huh?

Every now and then, I venture to an indoor range to shoot a bit, sometimes a 9mmx19. My old stainless Luger tosses the brass upwards, then then hits the ceiling, and goes forward. So I scrounge off the floor(harder to do now)for previously shot empties to fill my loss, no more; no less.

On some of the pickups I notice, primer piercings and evidence of blowby. Always thought it was the off beat load or just the pressure of the particular vendor, which gave the appearance of being right hot.

I rarely hear of a firing pin protrusion being too long, other than maybe in heavily used surplus rifles.

I once was sent from Europe a German gage(said it was from a war time bunker) for checking firing pin protrusion, just two notches, one on each end, go/no go; with a bunch of stampings. As usual, firing pin protrusion has to be checked at times I suspect; not a new requirement by any means.

In some hindsighte, I started measuring some of my free pickup brass, some was pierced primers. Most of the sampling was heavily below the SAMMI headspace spec of 754/776. I am a little light on Luger headspacing numbers right now, or European or other control specs. But here in the states, it seems(just a few measured items) that the 9mm brass is on the short side. This shortness might be contributing to some of the observations of abbynormal fired brass. A good hot load(9mm is fairly high intensity) with a short case in a long chamber, might be somewhat harder on things. I think that the result of a fired round is more controlled if it does not jump around so much unrestrained.

0.032" is a pretty large gap of a breeched up 9mm(754/776), which I think is pretty generous as compared to the 30 Luger, which is 10 in SAMMI. Guess some war type weapons were pretty generous in that spec, just wanted it to run sorta speak, saving brass was not the main agenda, kinda like ots ammo.

I think I might be more pro-active in measuring my brass, I seem to loose attention to detail at times. It has been noted, and I tend to agree, the Luger in 9mm likes a bit of length on the reload, within said spec of the day of course.

Hope the new barrel works out good for you, nothing like doing things for yourself and the knowledge of such.

Rick W.

[Kiwi Mark]

Hi, I found that when setting up the head space in the new barrel that I couldn't find a case that was on. 754". So used a case that was 0.750" and used a piece of paper as a feeler Guage as it is 0.004"thick. Shown in photo.
Perhaps Military Ammo has crimped primers to make up for the variations in head space, maybe a reasonable knowledgeable members may be able to let us know.