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Unread 11-01-2019, 01:22 AM   #1
HisSoldier
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Default Gass relief hole botom of breech block.

While searching info on fluted firing pins here I learned that it was not done to prevent damage from pierced primers, but I did find a mention of Finnish P-08's that had a relief hole under the breech block, likely from the front of the cylindrical bore for the firing pin, for that very reason.

I don't know if it's statistically a likely event but it sure sounds like it would be a costly one if it damaged the rear of the retaining lock area.

I'm an old machinist by trade and am wondering two things, 1. What is the Rockwell hardness of the breech block in that area? 2. How large is the hole and does it enter perpendicular into the bore where I mentioned, where the radius blends with the bore?
I have four candidates for this mod and if there is no downside to it I may want to add the hole to all of them. None of my Lugers, though all in near new condition, are "collectable", two '70's Mausers and two 1920 Commercials.






I hope this isn't the dumbest question in the forum's history!
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Unread 11-01-2019, 06:48 AM   #2
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I think your conclusion that 'none of your lugers are collectable' is wrong. I would not decrease their value by adding unneccessary 'features' to them.
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Unread 11-01-2019, 07:20 AM   #3
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Quote:
Originally Posted by HisSoldier View Post
I hope this isn't the dumbest question in the forum's history!
There is a lot of competition in that area.


be nice please
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Unread 11-01-2019, 09:21 AM   #4
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I have modified several breech blocks by adding the "Finn" hole; these were on mismatched shooter lugers. I'm not sure I'd modify a matching pistol; but then if you are going to shoot it why not? It is yours.

As to whether or not it is necessary- that is another can of worms. With modern ammo, correct headspace, and correct striker nose shape, condition, and protrusion- punctured primers are not frequent.

That said, I have fired .30 luger Fiocchi ammo with apparently very thin primer metal that punctured frequently.

The block is not hard, but I did use a carbide drill as that was what I had handy.

the size of the hole is about 3/32 to 1/8", it is not critical, but should be located just at the front of the striker bore, it is a vent. The hole is perpendicular to the bore.
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Unread 11-01-2019, 09:22 AM   #5
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Don, I have one of these, I forgot about the finn hole - hmmm
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Unread 11-01-2019, 09:26 AM   #6
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Quote:
Originally Posted by HisSoldier
I hope this isn't the dumbest question in the forum's history!

There is a lot of competition in that area.

I resemble that remark...…

Last edited by hayhugh; 11-01-2019 at 09:29 AM. Reason: second thoughts
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Unread 11-01-2019, 10:30 PM   #7
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Ok then, this is good news, it looks like a simple operation. I like simple.
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Unread 11-02-2019, 03:20 AM   #8
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Quote:
Originally Posted by HisSoldier View Post
While searching info on fluted firing pins here I learned that it was not done to prevent damage from pierced primers, but I did find a mention of Finnish P-08's that had a relief hole under the breech block, likely from the front of the cylindrical bore for the firing pin, for that very reason.

I don't know if it's statistically a likely event but it sure sounds like it would be a costly one if it damaged the rear of the retaining lock area...
The reason for the firing pin flutes, according to the patent involved, is to collect burned powder residue and reduce the possibility of fouling the firing striker. The assumption that they reduce the possibility of damage in the event of a pierced primer is the purest fantasy of undocumented "conventional wisdom," as there is no place for the high gas pressure to go within the breechblock body whether the firing pin is fluted or not. I have many friends on this board who will take umbridge and serious exception to this bald statement.

The most common damage from a pierced primer is the firing pin being forced backwards hard enough to break away the back of the retaining slot for the firing pin retainer, effectively destroying the breechblock.

I have had correspondence with a Finnish member of this board--If I remember correctly it was Juha--who agreed with the speculation that the Finns drilled the breechblock gas relief hole because the extraordinarily cold conditions there caused the metal of the primers to become brittle with the cold.

--Dwight
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Unread 11-02-2019, 04:21 AM   #9
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Doing this simple gas relief hole in two of my P-08's that for sure aren't collector guns I discovered that the Mauser 1970 4" 9MM pistol's firing pin is fluted full length, well, more correctly, it has a relieved or reduced band around the center leaving slightly larger circumference at both the front and rear ends (As all P-08
FP's have).

BUT these full diameter bands (front and rear) each have 3 very shallow grooves at 120 degrees and only a few thousandths of an inch deep (Shallow like rifling grooves engraved on a bullet, but straight) so that one could assume the intention was to allow gas to escape past them, OR, to just reduce the area of the OD to minimize friction perhaps.

They clearly won't act as pistons during a ruptured primer.

This was a total surprise to me as I only knew of the cylindrical firing pin devoid of reduced features or the later grooves that only go not quite half way toward the back. I should have snapped a photo I guess.
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Unread 11-02-2019, 06:00 AM   #10
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Quote:
Doing this simple gas relief hole in two of my P-08's that for sure aren't collector guns
How do you decide which guns are collectable or not?

You may have missed the fact that the 1970s Mausers have gone up in price and are being collected.

Drilling holes in them will not help to preserve or raise their value. On the contrary, its a good way to decrease value.

If you want to drill the heck out of guns, get a low grade 'shooter' P08 to play with.
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Unread 11-02-2019, 07:38 PM   #11
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Quote:
Originally Posted by HisSoldier View Post
Doing this simple gas relief hole in two of my P-08's that for sure aren't collector guns I discovered that the Mauser 1970 4" 9MM pistol's firing pin is fluted full length, well, more correctly, it has a relieved or reduced band around the center leaving slightly larger circumference at both the front and rear ends (As all P-08
FP's have).

BUT these full diameter bands (front and rear) each have 3 very shallow grooves at 120 degrees and only a few thousandths of an inch deep (Shallow like rifling grooves engraved on a bullet, but straight) so that one could assume the intention was to allow gas to escape past them, OR, to just reduce the area of the OD to minimize friction perhaps.

They clearly won't act as pistons during a ruptured primer.

This was a total surprise to me as I only knew of the cylindrical firing pin devoid of reduced features or the later grooves that only go not quite half way toward the back. I should have snapped a photo I guess.
Hi HisSoldier.

I agree with you here fully.

In fact, this seems to be the only "improvement" made on the 1970s Mauser pistols that is truly an "improvement".

Respectfully,

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Unread 11-02-2019, 07:50 PM   #12
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Mauser copied it from the Swiss 1929 model.
Innovative was the use of sintering in producing the pins.
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Unread 11-02-2019, 07:54 PM   #13
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Quote:
Originally Posted by Dwight Gruber View Post
The reason for the firing pin flutes, according to the patent involved, is to collect burned powder residue and reduce the possibility of fouling the firing striker. The assumption that they reduce the possibility of damage in the event of a pierced primer is the purest fantasy of undocumented "conventional wisdom," as there is no place for the high gas pressure to go within the breechblock body whether the firing pin is fluted or not. I have many friends on this board who will take umbridge and serious exception to this bald statement.

The most common damage from a pierced primer is the firing pin being forced backwards hard enough to break away the back of the retaining slot for the firing pin retainer, effectively destroying the breechblock.

I have had correspondence with a Finnish member of this board--If I remember correctly it was Juha--who agreed with the speculation that the Finns drilled the breechblock gas relief hole because the extraordinarily cold conditions there caused the metal of the primers to become brittle with the cold.

--Dwight
Dwight,

Did Juha offer any proof of his "hard primer" claim, as the pistol's metal should be the same temperature as the primers are.

Agreed that the fluted firing pins on vintage Lugers DO NOT provide any ventilation to prevent breach block destruction.

Respectfully,

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Unread 11-02-2019, 11:00 PM   #14
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"as the pistol's metal should be the same temperature as the primers are."

For sure, but what would that fact have to do with the observation that the thin, malleable primer cup metal becomes brittle?

The "metal" in the pistol is of different composition, shape , and thickness; and would be unrelated to primer failure- or am I missing something?
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Unread 11-03-2019, 08:58 AM   #15
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An older discussion of fluted firing pins:

https://luger.gunboards.com/showthre...ed-Firing-Pin!

These are the patent documents Dwight referred to:

https://depatisnet.dpma.de/DepatisNe...ge=1&xxxfull=1

https://depatisnet.dpma.de/DepatisNe...433A&xxxfull=1

There is nothing like going back to original material on questions like this.

This is a rough Google Translation of the second patent: DE90433a (Luger):

description
IMPERIAL
PATENT OFFICE

The present invention relates to further embodiments of the gas paths protected by D.R.P. No. 78406, which serve to to counteract the dangerous effects of the explosive gases which strike back on the firing pin when the firing gasses penetrate into the chamber as a result of defective ammunition and the like.

The purpose of the new facilities is to make it possible for the gases which have penetrated to pass through the gas paths as unhindered and rapidly as possible get behind the plate of the firing pin and into the interior of the chamber. For this purpose, either the plate of the So that, between it and the bore of the chamber, an adequate clearance is created as a gas path, or it can pass on the inner wall of the chamber, which lines the firing pin. its plate surrounded, or otherwise arbitrary matching recesses arranged for the same purpose. These grooves or recesses can be alone or in Connection with the other gas paths of the firing pin are applied.

Some such applications illustrate the examples shown, but by which the further possible embodiments still not exhausted. Thus, Figs. 1 and 2 in cross-section and partial axial longitudinal section of the chamber a Arrangement in which route the gas paths a on the plate a and leaf b of the firing pin nor the gas paths in the form of a channel on the inner wall of the chamber c are provided. The cross-sectional figures 3 and 4 show similar Facilities, where on the basis of the flattening of the plate on the firing pin resulting gas paths a still through recesses l in the chamber the gas paths arise. Furthermore, the same sections of FIGS. 5 and 6 show applications in which Gas paths around the striker plate a by different recesses are formed in the inner wall of the chamber.

Figs. 7 and 8 finally illustrate an embodiment in which the plate of the firing pin from the inner wall of the chamber protrudes so that the correspondingly far intermediate space .alpha. ' is formed to the gas path, which is equally good by Reduction of the size of the disc can be done by partial or total enlargement of the interior of the chamber.

To the backgating known in the axial direction retroactive gases no vertical attack surface of the
To hold the striker counter, his plate with advantage to the front, d. i. to the top beveled in one of the Fig. 2 corresponding shape.
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Unread 11-03-2019, 03:14 PM   #16
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Quote:
Originally Posted by DonVoigt View Post
"as the pistol's metal should be the same temperature as the primers are."

For sure, but what would that fact have to do with the observation that the thin, malleable primer cup metal becomes brittle?

The "metal" in the pistol is of different composition, shape , and thickness; and would be unrelated to primer failure- or am I missing something?
Don,

Yes, we are missing quite a few facts here.

You are "assuming" that Lapua Berdan Primers, from that period, were brittle when cold. Were they? A call to Lapua may solve this for us.

Also, the poor quality, hopelessly out of specification, 7.65 ammo you cite above, was not even made then. Relevancy?

Please further enlighten us with your research and readily verifiable facts.


Respectfully,


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Unread 11-04-2019, 08:50 AM   #17
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Sorry Seiger,
I did not "assume" the primers were brittle- the OP stated someone "else" said that, I was only questioning why the temperature of the pistol would matter- If this were true.
Personally I don't buy the brittle primer story---


The mention of today's Fiocchi is relevant to the idea or desire to add the relief hole to a pistol for shooting today that does not have one- as the OP mentioned.

I have posted photos of the "holey" Fiocchi primers, and of the added gas relieve hole- these are readily verifiable. It is clear that the added hole gives gas a place to exit the bolt, which does not exist in the original design.

It is gratifying to note that now we all seem to be in agreement that the commonly seen fluting does absolutely nothing to allow gas escape. The Swiss and Mauser mods, may give a little improvement- but I have not studied them; since I have neither "brand" luger.
Perhaps this often repeated, but wrong, tale will die now, or soon.

Now please explain why you even mentioned the temperature of the pistol metal?
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Unread 11-04-2019, 09:19 AM   #18
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Sorry Seiger,

It is gratifying to note that now we all seem to be in agreement that the commonly seen fluting does absolutely nothing to allow gas escape. [/COLOR]
Based on the second Luger patent on these flute cuts in the firing pin, I don't think we agree on that. The patent expressly states:

"The purpose of the new facilities is to make it possible for the gases which have penetrated to pass through the gas paths as unhindered and rapidly as possible get behind the plate of the firing pin and into the interior of the chamber."

The "chamber" mentioned in the patent is not the one that holds the cartridge, but rather the one that holds the firing pin inside the breech block.

This would seem to describe the objective of the fluting cuts was to allow gas to escape when a primer is pierced.

How else do you read this?
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Unread 11-04-2019, 02:20 PM   #19
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Mrerick,
That patent(by Georg Luger and not a "luger" pistol patent) and those grooves are entirely different from those in the luger pistol as modified according to the 1930 change.

What you show is a rifle bolt, which firing pin has a circular flange- and indeed it does have grooves cut into the flange.

In this case and shown in the drawing, gas can pass the flange into the bolt body and escape.

In the luger bolt with grooved striker the grooves are not deep/long enough to reach any area of the luger pistol breech bolt where the gas can escape.

You have confuted a separate and entirely different use of grooves to support what should be a debunked and spurious interpretation of the purpose of the pistol striker grooves.

All one has to do is Look at the grooves in a luger striker, study the placement and their relation to the bore of the luger bolt- there is NO other conclusion.

The luger striker grooves do nothing to help or let gas escape!

I don't interpret the patent as it has nothing to do with the luger pistol.
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Unread 11-04-2019, 02:46 PM   #20
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Luger frequently patented features on one gun type and then licensed his patents to be used on other types. Quite normally, as many features will work just as well on a rifle and a pistol.

Anyway, I think the flutes help in both situations: clearing muck and some gas relief.

The point remaining is that drilling holes in breech blocks of decent guns does not help their value.
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