Luger Frame Ear Study

[mrerick]

A recent post about the profile of frame ears got me thinking about their variations in shape and profile.

Attached are photos of several Lugers form all production eras (which is why I posted this in General Discussions rather than one of the targeted forums).

There is considerable variation in the transition from te horizontal area that the toggle train rides along to the curved area that the toggle itself rides up to unlock the breech and permit extraction and ejection.

There is so much variation that I wonder if this small initial transition area was more a function of individual technician operation technique and the diameter of the milling tool rather than fixed jigs.

The position and curve of the long portion of the ear itself determines the timing of a Luger's cycle and must be precision cut. This must have been a function of jigs and subject to acceptance gauging in the factory.

Here are several Luger variations from DWM, Erfurt, W+F Switzerland, Simson, Mauser and Interarms/Mauser:

[mrerick]

Additional Variations:

[Sergio Natali]

Mark


Good pictures, good help, saved for future use.

[Edward Tinker]

this is an interesting spot to notice too..

[Vlim]

The 1970s frames come in two shapes, but these are independent of the caliber.

The early 29/70 frame copied the Swiss 06/29 design and was only found to be suitable for use in .30 luger versions. The 1973 variation is suitable for both 9mm and .30 luger. The ears were located about 1 mm further to the rear, this corrected reliability/feeding issues with several barrel lengths and the 'Swiss style' toggle ramp.

[FNorm]

If I remember correctly, there was quite a write up on this in the Krieghoff book.
Or someplace????

FN

[G.T.]

It's interesting on the different machined shapes?... But, it would seem to me, that you would need some type of comparative overlay to arrive at any definitive conclusions?... Vlim's print shows it well... Comparing something to something... got to have a starting point? .. To find an end point, to find a mid point, etc, etc, (I would assume the DWM print?...) It would be a neat project for someone that can make a computer obey his commands??? It sure as hell ain't me.......... I'm happy when the damn thing just turns on!!!!..... Best to all, til...lat'r....GT...

[Sergio Natali]

FWIR I've only read something about comparisons of the "rear frames" (page 31 of Randall Gibson's book of Krieghoff) but I don't seem to recall anything else.

[mrerick]

The area that Ed circled in his post is the main reason I posted these comparison photos.

There is considerable variation in this area. It looks like the different manufacturers used a different diameter milling tool, but also that the technicians doing the milling added variability in this area. It's possibly a unique signature for an individual Luger.

The shape and position of the rest of the front edge of the ear is critical to the timing and operation of the Luger. Even very subtle changes to this profile (as highlighted by Vlim) will change this timing.

There are also subtle differences to the inside profile thickness along the inside edge of the front of the ears. These don't affect operation, but also provide a shape signature.

I don't have any Krieghoff Lugers to post, but I do have the Gibson book and will check it out...

Marc

[spacecoast]

Interesting study.

Since it's a little difficult to compare them picture to picture, it might be instructive to remove the upper from the frame and then trace them one after the other on a piece of paper, with a small, consistent horizontal or vertical separation, similar to the diagram Vlim posted.

It could be a bit time consuming, but might show interesting results. I'd also like to compare multiple examples of the same model and see if there's any natural variation in the position and curvature of the "cut" down to the main part of the frame.

[sheepherder]

Originally Posted by Edward Tinker

this is an interesting spot to notice too..

Are you referring to that 'notch'? The area where the curve transitions to the straight top of the frame? I would agree that it is odd that they made this transition area 'angled' rather than a square corner. The toggle knob never comes close to the top of the frame, something like ~.080" clearance. The knob hits the curve full contact right above the 'notch', so why have an additional milling cut to make it 'angled'???

[Sergio Natali]

Originally Posted by FNorm

If I remember correctly, there was quite a write up on this in the Krieghoff book.
Or someplace????

FN

Originally Posted by mrerick

The area that Ed circled in his post is the main reason I posted these comparison photos.

There is considerable variation in this area. It looks like the different manufacturers used a different diameter milling tool, but also that the technicians doing the milling added variability in this area. It's possibly a unique signature for an individual Luger.

The shape and position of the rest of the front edge of the ear is critical to the timing and operation of the Luger. Even very subtle changes to this profile (as highlighted by Vlim) will change this timing.

There are also subtle differences to the inside profile thickness along the inside edge of the front of the ears. These don't affect operation, but also provide a shape signature.

I don't have any Krieghoff Lugers to post, but I do have the Gibson book and will check it out...

Marc

Marc

You're right, it seems to me that every make had its own measurements, and that these were probably checked and hand fitted one by one.

[Lugerdoc]

Vlim, i also find it interesting that the M29 & Parabellum frames shown have a quicker opening toggle than all of the German military frames shown. If this is because of the 7.65mm vise 9mm caliber, what is the comparison to the early DWM 7.65mm M1900 and 06 long frame lugers? just reinforces my belief that "not all luger parts are interchangable". TH

[G.T.]

Hi to all, in re-visiting the pictures it appears as if the 06/29 Swiss & the 70's Parabellum are designed and machined to follow the ramp almost immediately upon recoil and look to have a near symmetrical shape when compared to the toggle knob dia. ... As these were both later designs / copies / etc. maybe by time they were made, and in the case of the 70's Mauser, re-introduced, they had learned something that either reduced recoil, or improved function?... I'm pretty sure the "bear strong" magazine follower springs were an attempt to overcome some unforeseen or newly discovered deficiency, maybe the ramps were a corrective measure as well ?? I can remember on snowmobile racing clutches, the counterweights had curved ramps milled on the face to run against corresponding rollers. The curve, weight, length and contact point, (and other factors) had a tremendous impact on performance?... I would suspect the same on a Luger, as far as finding a sweet spot goes....... When all was said and done, it could very well be a compromise for both calibers?... As in we've messed with this long enough, lets go!... .. Best to all, til...lat'r....GT
BTW, if you were going to compare all of the ramps... The constant starting point would be the toggle knob diameter, (actually, bisected circumference?) all the ramp profiles could be graphed off of this one constant.... as it would track travel distance, curve/rate, and location, (high/low)?????? Maybe...

[Vlim]

Hi Tom,

Since Switzerland only used their own .30 luger ammunition, they had the time and the possibility to tweak the design to match their ammunition. It did come back to haunt them when they tried to introduce the 9mm round. They had quite a few problems getting the 9mm to perform reliably and accurately in their M1929 pistols.

Mauser eventually solved the issue by moving the Swiss curve about a mm to the rear, so the guns repeated properly with different barrel lengths and different calibers (.30 luger and 9mm).

This opening curve problem was the reason that Mauser initially only offered the new Parabellum in 4" 9mm and 6" .30 luger. The rest was too unreliable and they had already produced a large quantity of frames they didn't want to scrap either.

So in the Mauser parabellum design you will also find 2 styles of frame ears. The older 'Swiss' type and the newer Swiss curve, 1mm to the rear.

[mrerick]

It would be possible to get dimension accurate images of these ears by using a flat bed scanner instead of a camera after removal of the safety lever. . That would allow very high resolution measurement and comparison.

It's a project to take out all the guns and do this...

In any case, this is an interesting area with quite a bit of variability between Lugers and the possibility of a unique "signature" for individual guns at the "notch" area that Rich mentions. I think that this "notch" area may not be a critical cut for proper operation as long as it's far back enough, and the shape variance likely reflects both different tooling and technician operator actions when milling the area.

Marc