Fluted Firing Pin

[Dwight Gruber]

Thoughts on this have been rolling around in the back of my head for awhile. Recent discussion of a Finnish pistol brought them to the fore, so I went back and found the last discussion of the topic which referred to a patent; it can be found here http://forum.lugerforum.com/showthre...t=fluted+georg

I've un-buried the discussion with this new post, with a quote from the last post of the original thread:

Originally posted by Edward Tinker
...Those were just a few items [sear safety etc.] that occurred to me that were changes to Georg's design / improvements, so I wondered if it was a committee or other change for the firing pin?

Interesting thoughts and makes you wonder? I will re-read Walters book and look for that. He stated in the Luger Book that he made it less encyclopedic, does that mean in the previous book he might have listed where he received this information (or is this the only mention of this action?)

Ed

I quote here Walters' entry in "The Luger Book" (1986) :

" F22 Firing Pin
Early pins had plain cylindrical heads. By 1934, however,
grooves were added to prevent obstruction by excess
grease and oil. Ironically, this had been patented by
Georg Luger (for rifles) as early as 1893:
see DRP 78,406 and 90,433."


It is a common recommendation hereabouts that shooters should replace their plain firing pins with fluted ones to disperse the pressure of blown-back gases in the case of a pierced primer. Here is part of another post in the same discussion:

Originally posted by Johnny Peppers
I think this has been asked previously on the forum, but is there any reference to the firing pin being fluted to allow gas to escape in the event of a pierced primer or is this urban legend? [Walters' "Luger Book" reference omitted--DG] Apparently Georg Luger saw no reason to incorporate this into his pistol's firing pin.

If the flutes were indeed added to allow gas to escape, there were no other previsions made to the firing pin or breech block to vent the gasses. One of the tests on the .45 Luger was to fire it with a cartridge with a pierced primer followed by two normal rounds to see if any damage was done. From the report there was no damage or problem after the test.

Logic suggests that, indeed, the fluted firing pin would be completely ineffectual in gas venting. The flutes themselves comprise no more than a few cubic mm relief volume. I don't know the gas pressure released with a pierced primer--it could be calculated, and other correspondents here may have the figure. It has been the reported experience in these Forums that pierced primers have destroyed the breechblock of the Lugers involved (these are old guns, remember); a few cubic mm relief space is not going to relieve that kind of pressure.

The question is, really, where do you effectively redirect the gas pressure in the event of a pierced primer? The firing pin/channel in a Luger breechblock is a closely-machined fit, and makes a reasonably effective gas seal, at least to impulse pressure. The only aperture in it is the groove cut for the sear. I checked my 1936 S/42; there are three flutes cut each at 90�° to the other in the striker; there is no flute cut in the quarter parallel to the sear. In addition, the flutes themselves end fully 10mm ahead of the sear cut in the breechblock. It is apparent that the sear groove will not relieve impulse gas pressure.

Finnish armorers apparently devised an effective gas release solution. Finnish Lugers can be found with a small hole drilled into the bottom of the breechblock, right at the back end of the notch cut for the holdopen to catch. This hole is enters the firing pin channel within the cavity formed when the firing pin is back in its cocked position, where it would be forced in the event of a primer breach, and provides a vent in that eventuality. Luger production which supplied the Finns occurred before 1934.

This is not to say that the flutes do not serve a very useful purpose; that purpose is the original pointed out in Georg Luger's patent. As noted before, the firing pin channel is a rather close fit, and grease and dirt can impede the effectiveness of the striker. Examination of a fluted firing pin after a few hundred rounds firing amply reveals the flutes' effectiveness in collecting grease and powder residue. This is perhaps another reason they would make poor gas pressure channels, as this blockage would impede gas flow.

I humbly sugggest here that the practice of changing to fluted firing pin for the protection of the breechblock in case of a pierced primer is unnecessary and deceptive, as it cannot offer this protection.

There is a good reason to change a firing pin for shooting, and oddly enough, a fluted firing pin is a good choice. Classic Lugers are nearer the end of their use life cycle than the beginning. In a small survey of parts which commonly break in use http://forum.lugerforum.com/showthre...n+parts+survey it is demonstrated that firing pins are in jeopardy. In order to protect a matching-numbered firing pin from breaking (thereby reducing the value of the gun), it is worthwhile to replace it for that activity. The value of a fluted firing pin in this circumstance is that they are relatively newer (from 1934), and should be less prone themselves to breakage.

--Dwight