How Hard Is My Luger...?

My new R. Gibson Krieghoff Parabellum book talks about a Rockwell hardness test on the metals comprising parts of the luger especially the frame and receiver. Itâ??s a test apparatus that punches little indents on a section of metal and measures the force needed to make the indent/nipple mark a certain depth. The higher the Rockwell hardness number, the harder the metallurgy.


Mauser, Simpson, and Krieghoff all typically had numbers of B-31, B-33, and B-32.


The Weimar and Imperial lugers from DWM, Erfurt, and Spandau all had numbers of B-22, B-21, and B-21.


Surprisingly, all Swiss Bern made lugers (actually made by the Swiss) have numbers of B-10 only.


It seems the Germans went to a harder metals over time, while the Swiss stayed with a very soft metal. I would guess this allowed the Swiss tooling to stay in production longer, but probably means the Swiss Bern guns can wear out much sooner with shooting and might also mean they can get scratched or dented much more readilyâ?¦


Interesting how when you read about Krieghoff lugers you end up learning something about Swiss Bern lugersâ?¦

[AGE]

Careful, hardness isn't everything. It all depends on the metal. It's true that some alloys when properly heat treated get stronger, tougher and harder. However, others get brittle as they get harder. Just testing for hardness without knowing the rest of the alloy composition can give misleading conclusions.


AGE (Registered Professional Mechanical Engineer)

[Dwight Gruber]

A practical slant on the topic, I recently talked to an engraver about engraving a Luger. He told me that he (and some other engravers) won't work on Lugers, because the steel is too hard. The frame may or may not be engraveable (he suggested that there are hard and soft spots), and that engraving tools just scratch the toggles. He also revealed that some engravers get around the problem by heating the steel up enough to reduce the hardness, and then re-harden the steel when they are done He also related a scary story where an engraver of his aquaintance put the toggles back together and into service without bothering to re-harden them.


--Dwight

[Marvin]

Pete,


AGE is correct about the type steel and the type hardness used on Lugers.


The Rockwell "B" number, or scale, you refer to is the Brinell Scale which is much more commonly used in Europe than the US. The US tends to use the Rockwell "C" scle for testing purposes. Yesm the higher the number, the harder the surface.


On firearms, Most of the parts are not that hard since the metal must also "give" during the firing cycle or the metal would break like a piece of glass. The steel used in firearms have sontinually changed over the years and the Luger steel was no exception. As the years progressed from the late 1800s to the mid 1930s when Mauser took over, the steel composition did change and better steel was availalbe. In addition, heat treating control changed so a better quality product could be produced.


The hardening on firearms only needs to be the surface for most parts for wear only (note: there are exceptions to every rule). If the part/s is hardened to deep, it will be "brittle" and break like glass. As steel is used over the years, the continual flexing of the steel will cause a part to break too. Take a regular clothes hanger and start bending it at the same place several times, you will notice that that spot gets very hot and breaks quickly. This piece of steel (yes, it is low quality) breaks from the hardening process created by the heat, and also from the flexing. This is similar to what happens to a firearm part/s every time it is fired. Eventually, something will break.


A properly designed part, with the proper heat treatment, will last for many years without braking unless it is abused! As I have stated before, Lugers (and other pistols) made from stainless steel are not as strong as carbon steel. Stainless steel is not as strong as carbon steel, will wear faster on mating surfaces, but since the material is softer, it will"bend" or "flex" before it will actaully break.


As to the gunsmith that said the toggle of a Luger was so hard that the engraving tool would not cut maybe correct. I have not tested the hardness of the toggle or the breechblock, but the surface must be hard (I would guess in the 45-50 Rc scale, but this is not as hard as the tool which should be in the 50-55 Rc scale range). If the surface IS that hard, the surface hardness is only 1-1 1/2 thousands deep, with the rest of the steel soft, which should be in the 20-25 Rc scale range. Most firearms hardness is on the surface only for wear and leaving the soft core so the part can still bend and stretch without breaking. A case hardened part is like an M&M candy; hard shell, but soft inside.


This got a little long, but I hope it helps explain a little on the hardness of firearms. Firearms are not as hard as most people think they are; just the parts which have a lot of wear. The toggle pin on Lugers are one of the hardest parts I THINK, since it has a lot of pressure and wear, but does not have that much bending stresses due to it support on each end.


Marvin

I hate to be the "Bringer of Bad News" But,Rockwell "B" scale number is not the same as Brinnell number.

In fact the two are separated by about a factor of 2 at the hardest end of the scale and by a factor of about 3 at the softer end of the scale.

So the only relation between the two are by a comparison chart that relates all of the different methods of hardness testing values.

Sorry to have to correct you but it could be a fatal mistake to mix the two values.

ViggoG

[Marvin]

Viggo,


You are correct! Don't ever feel bad about corrections. It was a dumb mistake and I know the difference completly. It could have caused a lot of confusion if anyone had looked up the different scales.


Marvin



P.38 Forum

The information is great! I never knew this before!


KUDOS TO PETE!


Tim Canney