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!

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.

There is a lot of competition in that area. :D

:soapbox::eek:
be nice please

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.

Don, I have one of these, I forgot about the finn hole - hmmm

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...…

Ok then, this is good news, it looks like a simple operation. I like simple.

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

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.

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.

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,

Sieger

Mauser copied it from the Swiss 1929 model.
Innovative was the use of sintering in producing the pins.

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,

Sieger

"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?

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.

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,


Sieger

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?

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?

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.

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.

I think, and this is only my opinion, that if "pierced primers" are a regular problem, then....
1. You should examine the firing pin for damage to the tip, as the pierced primer will gas cut the tip, and exacerbate the problem, only causing MORE pierced primers.
2. Immediately discontinue the use of the primers, or ammunition that is causing the problem. As civilian "hobby" shooters, we are not typically using our Luger pistols in battlefield conditions where we are "stuck" with issued or scrounged ammo. We have choices in the ammo we use. Seek other ammo. The cheapest ammo will usually give the cheapest results. Your mileage may vary.....

The flutes cannot help with gas relief in the luger striker/breech bolt arrangement, one just has to look at the interaction/fit of the pieces to observe that.

If the grooves were cut farther back to allow gas to escape from the bolt bore, they would act as a gas relief pathway; but they lead "nowhere".

The arrangement of the firing pin/striker in the bolt shown in the patent drawing is an entirely different design, and the grooves Do lead to an escape route for the gas.

The OP was advised of the possibility of downside to the value or saleability of a collectible luger if modified.
Now it is his choice to proceed or not.

The flutes actually can help to relieve some gas pressure.

If you look closely at a P08 firing pin, you will notice that the front area has a raised surface, which rides against the inside of the breech block. The body of the pin is actually slightly thinner, allowing for space between the pin body and the breech block channel.

The flutes in a fluted pin should cut through the raised surface at the front, allowing escaping gases to flow past it, along the thinner area of the pin towards the side of the breech block.

Perhaps we should set up a small lab test, putting some air pressure on a breech block via the pin hole and observe the amount of pressure exerted onto different firing pin designs: normal P08, fluted P08, Swiss.

I think pressure relief is possible, although limited, with both the fluted and Swiss designs, while the Original non-fluted P08 design will work more like a piston.

Come to think of it, putting a breech block upright and pouring a liquid through the firing pin hole should also show which version allows 'breathing'.

Adding the flutes to the firing pin increased the production expense of the part as the three grooves had to be cut / milled into the original part design.

WW-I production of the Luger at DWM and Erfurt did not incorporate this modification, delivering roughly 2 million military contract Lugers to the Germans and more to other commercial customers - all without the firing pin relieved with flutes.

New features with added expense are rarely added to a military contract without the customer requesting them. "Here - we've got this great new idea to keep the cylinder cleaner so we're adding labor and this cost to the contract to make this change"? Were dirty firing pin cylinders within the breech block ever documented as a problem?

Yet, the grooves were added by the time Mauser started producing them. I think it's reasonable to conclude that the design was changed to solve a problem, and that the additional expense of cutting the grooves was justified by some experience. Until documentation is found specifically explaining why the cuts were added to Luger firing pins, all we can do is speculate.

It is not normal for exhaust gasses to be vented out the firing pin hole of the breech block and through the cylinder inside the breech block that the firing pin rides in. This only happens when a primer is pierced and high pressure gas vents into the hole within a still locked breech.

This is why I think that it's unlikely they were added to solve a fouling or dirt problem, even though it's possible that the grooves somehow helped. With two million Lugers in the field, is it likely that the change was made because of fouling? I'd consider it possible, but unlikely.

But we do know what happens when high pressure gas vents into the firing pin hole of the breech block while the breech remains locked. It drives the firing pin like a cylinder into the spring retaining guide and exerts high pressure against the small locking tab that holds that pin into the rear of the breech. The back of the breech block breaks apart destroying it's ability to hold the firing pin spring guide in place. SAAMI spec today for a 9mm Luger is 35,000 PSI, and something similar would have been driving that firing pin back in WW-I Lugers.

In my opinion, repeated observation of that kind of damage by field and unit armorers would have been enough to justify the expense of cutting the flute grooves into the firing pins. It is a more likely justification than issues relating to fouling. The rear of the firing pin guide fits a bit looser in the breech block than the face of the firing pin, and the grooves would be expected to reduce the striking force and the impulse pattern of the pin against the guide.

This was likely tested empirically by the gunsmiths at Mauser and found to be slowed and reduced enough to stop the cracking of the breech block area that retains the spring guide. The timing of the movement of the firing pin could have been delayed slightly allowing the breech to unlock before full pressure was applied to break out the firing pin guide tab retention. That is, of course, speculation - but it could be tested and verified today.

Until documentation is found, this has to remain speculation. I think that the patents Dwight pointed out in the earlier posts do inform us on why the feature was designed.

Refer to Goertz and Sturgess, Pp 1073-5(green edition); for more discussion.

The original purpose for the grooves, ordered to be added by the Reichswehr, and before and separate from any Mauser involvement- was to allow powder buildup and oil/grease a place to move away from the front of the striker.

The possible, but small improvement in gas venting, mentioned by Vilm, would depend much on how large/long the individual grooves were cut; but, gas venting was not the original or main concern when the grooves were ordered.

A very small percentage of groves that I have observed will reach the sear cut out- but very few.
The observed radial location of the grooves is random. IF gas management was important and the actual/main reason that the grooves were added, the position of said grooves would not be random, but at least one groove would be centered at the sear cut- and made deep/long enough to reach the cut.

Marc is correct that most/much of this discussion is opinion or speculation, especially the speculation that Mauser "tested" the previously ordered and established grooves- Mauser would have had no choice but to continue an approved and ordered design feature. JMHO. ;)

If Georg Luger thought his bolt patent covered the luger pistol striker, I believe we can be sure he(or his heirs) would have insisted or at least tried to be paid for that "improvement". Again JMHO. :)

I think this horse is well and thoroughly dead now, and I'll stop writing about it. :)

I just looked up Sturgess (red edition) on page 1115 where he discusses the modification.

Sturgess describes better performance because of reduced fouling, with the problem being light primer strikes when the firing pin was fouled inside the breech cylinder. The fouling was likely accumulating inside the cylinder in front of the firing pin near where it's face almost contacted the breech block around the pin hole.

Sturgess also acknowledges that an alternate purpose is protection of the breech block in a pierced primer situation.

So... both benefits were considered by Sturgess. A good idea never goes to waste.

Vilm,

As is quite usual for you, this is a brilliant idea, that should completely answer all questions on this matter!!!


Sieger

Don,

Gott sei dank!


Sieger

Don,

OUCH!!!


Sieger

A good chance that the flutes were introduced after Luger's dismissal and his death on purpose. It would have been a lot cheaper.

Luger made a small fortune on royalties when he was still active, a situation that the manufacturers have tried to avoid ever since.

Also one point to consider is that the early gun lubricant of choice in the old world was grease, not gun oil. Early manuals refer to the use of stuff like vaseline. Also remember the grease bottles issued by the Swiss and the grease containers on navy, dutch, Portuguese cleaning rods. So it is funny that the introduction of fluted pins on the P08 came together with the introduction of more modern gun oils, as also used in the RG34 cleaning kit. Doesn't add up, really.

I wonder what the OP decided.
HisSoldier? :)

I hope vaseline will not be part of the decision :D

Me thinks he didn't make to the end of the pie fight...I mean discourse. On a more serious note I found it very educational. Thanks folks. :thumbup:

I did the operation to two P-08's, the first was a 9MM 1970's 4" barreled beauty which only had one flaw for me as a shooter (this was many years ago) I cut the grip safety off and modified the safety to function normally, without the grip safety pinching my hand. I have no particular dislike for grip safeties and like them in all my 1911's, but the Mauser GS was very poorly designed IMO. After modding the safety to act as a normal safety I filled the slot at the back of the grip panel with wood my GS gave me and he checkered the plug so it wouldn't show.
So, that Mauser is not a collector, it's a shooter. The other Mauser I have is a 6" barreled 7.65 MM, in new condition and I think never fired from the factory, so, since I don't shoot it I decided to not alter it.
The other P-08 I altered is a 1920 commercial which has matching numbers but not a matching magazine, it's 6.35 MM and shoots nicely, and it also looks near new. I figure without a matching magazine it's not highly valuable either.

The fourth P-08 is also a DWM 1920 Commercial WITH matching magazine, in 6.35 MM again of course, and it also is in very pristine condition, even better than the other one, I decided to leave it alone and don't shoot either it or the 7" 1970 Mauser, so, since I don't shoot them I see no possibility of a pierced primer causing bolt damage.

What is that supposed to mean Vlim? Is that something you are familiar with using somehow in your guns? Must be a European thing.

But back to the 1970's Mauser firing pins, yes, they have shallow grooves that go all the way to the back of the FP, but why they put them there is a mystery I guess, though I think they would bleed enough gas back past the pin to prevent the damage, so I did probably drill the 9MM gun's block without good cause.
But again, it's probably not a collector anyway and does no harm IMO. I originally was going to drill all four breech blocks but based on the opinions here about hurting value I decided to not do it to the two that may have some slight collector appeal, and we all know, guns that aren't that collectable today sometimes become so tomorrow.

Must be painful to have modded a nice gun to a shooter. But the grip safeties are still available as spares here and there.

So why not return the pistol to its original configuration and actually improve the value?

I guess the others are .30 luger, not 6,35.

Anyway, I think collecting is about preserving, not about market values. A nice 1920 commercial without a matching mag is still worth preserving, whatever the value may be.

HisSoldier,
good logic and the choice was yours to make.

Some folks "collect" to shoot; others have scores of individual reasons for collecting.

I even collect "non-collectible" pistols at times; just because I like them. :)

I always get a bit grumpy when people say something is not collectable.

Everything is collectable, depending on the demands and reasons of the particular collector. Value, completeness, finish, technical state are not simple tick boxes that decide if something has a place in a collection, or not.

If it's in a collection, it is collectable.

Furthermore, I hate to see people ruining perfectly good guns for the wrong reasons (including convincing themselves it's ok to drill holes in things because they consider it not to be of high enough value). But that's my take. I'm in the preservation camp.

Aw heck! Yes I meant 7.65 X 21 MM. Have been looking at rare 6.35's and I had them on my mind.

I bought the 9MM late repro P-08 as a shooter, and since then had heard many folks put them down over many years, so #1. I was convinced they would never be that valuable, and #2. I had no intention of shooting it with that lousy GS biting my hand.
But as for safe queens, I'm not of the opinion that owning a gun automatically means I have to shoot it, and that seems to be the position of the majority of people in other forums. I have a few "Safe queens" and I enjoy them for some weird concept about preserving them for posterity, which means I have to pay to become a museum curator from the time I buy such a gun until the rest of the world admits it is rare and valuable.
I once saw an ad in GB for a dished toggle knob P-08, the seller said it had remained unfired in nearly new condition, owned by a fisherman in Alaska until he died. His son inherited it and took it out and shot a magazine through it!
My first thought was that he could have had the same "experience" shooting a $700 shooter and not lost a dime of it's value.

I just realized I called the dished knob pistol a P-08, which it wasn't since it was pre-1908. It was the Model 1900 Parabellum. It occurred to me that I might be called to task for that.

Just "shooting" a mag through a 1900 or another luger will not cause it to lose any value.

Now if you were to drop it on concrete or store it in a wet holster or break a part or lose it-
That would affect the value.

JMHO ;)