"Pinned" Interarms Mauser Grips ???

[sheepherder]

Alvin posted (at Still's) about the 1970's Interarms Mauser Lugers having "pinned" grip panels...

Interarms Luger works fine. The pinned grip panels could be a little bit troublesome, but that's a design issue, not a manufacturer quality control issue. And that can be avoided with a little bit preventive measure (for example, put a wide rubber band around the grip can prevent breaking the pin hole inside the grip, and also disable that grip safety). I tested fired a 9mm sample 20 years ago -- an Interarms Luger and a Portugal assembled High Power Browning, both were bought NIB, even Browning jammed once in the range, but that Interarms with Swiss style straight grip worked perfectly without any failure.

Does anyone have pics of these??? I have not come across any reference of this before and would be very interested in seeing pics.

I recollect that they had straight screw cutouts rather than the curved WWI/WWII grips, but where are the pins???

[alvin]

I still had the old pictures.

1970's Interarms Luger's grip panel was hold in place by a pin mounted on the pistol grip frame. For collector never shoots the gun, that's not a problem. But this design was wrong, the pin hole on the grip panel is too close to the edge of the internal routing, so hole on wood is very fragile and could easily break in range. When the hole is broken on wood, the pin could not hold the panel in place anymore and the panel moves, operator will notice it's not easy to remove empty magazine due to the moving path of the magazine release latch is blocked.

Sometimes, I wondered this: say, Mauser engineers are professionals, why didn't they see the obvious issue like this when they made this change... but engineering design is engineering design, mistake did happen from time to time.

As mentioned in the post, putting a wide rubber band on the grip could prevent that from happening in range. That band also disables the grip safety. One stone kills two birds.

[sheepherder]

Thanks for the pics!

This is an odd modification. Like you, I can see no need for it. Do the tops of the grips still 'tuck into' the frame as the P08 Lugers do??? Are these pins supposed to stop grip movement???

It was in my mind, following recent postings in the For Sale forum, that I might like to purchase a nice Interarms Mauser Luger. Now I'm not so sure.

The straight-cutout grip mod did not bother me too much as I saw that Numrich had new Interarms grips, but now I wonder what other 'improvements' Mauser made???

[alvin]

The top of the grip does tuck into the frame. From this failure, I figured Luger's way of holding panels in place: its bottom position was fixed by big screw, its top tucks under frame, that prevents panel from flipping off, but with those two, the panel could still swing a little bit back and forth. On P08, that swinging was prevented by a wood ridge routed on the inside of the panel. On Interarms, the ridge was cancelled, replaced by this pin. This change probably was considered be an improvement by engineer, but actually it's not.

Other than that, the gun works great. I tried single shot, double tap, fast firing, all worked fine. Luger's grip size is a little bit too big for me, but it's still holdable.

[Edward Tinker]

Rich, do you have Vlim and Mauro's book?

It goes into detail about changes and how they were made...

[DonVoigt]

Just another short cut "they" made/took in production of these late Mausers.

[sheepherder]

Originally Posted by Edward Tinker

Rich, do you have Vlim and Mauro's book?

It goes into detail about changes and how they were made...

No to the book. I just had not seen this mentioned, even in the discussions on the Interarms Luger grips. Not even the absence of the wood 'rails' that the pins replaced.

Learn every day.

[alvin]

It's a weird change. I did not see how this could save much production cost. Putting this pin there also took effort. They used cast steel, that could save cost in pre-CNC era.

[DonVoigt]

Originally Posted by alvin

It's a weird change. I did not see how this could save much production cost. Putting this pin there also took effort. They used cast steel, that could save cost in pre-CNC era.

That's cause you don't make "stuff"; the work/cost savings is in the interior grip shaping that was eliminated, and overall simplification of the grip and its fitting to the frame

[alvin]

On outside, that diamond checking on wood took effort. But on reverse side, wood cutting via a routing template on a flat surface is supposed being very simple. No kidding, people consider making dovetail joint being complex... only complex if using hand tools. With router and a proper template, even amateur could do that. The reverse side of Luger's grip panel is not complex.

[ithacaartist]

A pic of grips from my Mauser Parabellum 29/70...

These original grip panels have two steel pins, using an approach that locates the pins in an area that will stand up to the stress of firing, as well as requiring no extra work to install a pin in the frame. They are not quite round cross section on their ends, and may have been filed to fit. Epoxy is on the scene, as well, and I suspect that it is not original.

The Erma KGP series uses the pin-in-frame concept. The successful one is the walnut type, a hole in the flat back side of the scale, in very sturdy surroundings. Their failure is their engineering of the index pin's accommodation in their plastic grips. The classic breakout has occurred--as you can see--kind of the equivalent of the damage to the wood grip, but expressed in plastic. All that resisted the forces of firing was a wall circle of styrene.

Alvin, the profile of the back of the grip is simple, yes, but it must be executed precisely!

[alvin]

The panel would need a little bit fitting, that's true. But comparing with steel against steel fitting, wood against steel fitting is relatively simple due to wood is soft material. Before plastic pistol appears, most pistols depended on the pattern on the back of panel to prevent it from swinging, that's not Luger specific. Using a pin for that purpose, although less common, it was not an innovation either, that works too. The failure came from the position of the hole and the diameter of the pin, its strength must be put into consideration. Using a needle-like pin on a wood hole near the edge was incorrect. The engineer who designed this specific change obviously ignored that.

[Vlim]

Mauser looked into these modifications as the original P08 grips also had the tendency to move around on the frame, especially with age when shrinkage took place.

The initial 'fix' was to install the 2 metal pins in the grip edge, but this meant that the grip edge was quite pronounced and not that comfortable to hold.

The next solution was the small pin through the frame that would spike the grips in place. Worked better, but again, with use, the pointed pin would wear out the hole and develop play.

The best solution is not to use wood as a grip material

[hayhugh]

I also had this problem: http://forum.lugerforum.com/showthread.php?t=36002

[DonVoigt]

Originally Posted by alvin

The panel would need a little bit fitting, that's true. But comparing with steel against steel fitting, wood against steel fitting is relatively simple due to wood is soft material. Before plastic pistol appears, most pistols depended on the pattern on the back of panel to prevent it from swinging, that's not Luger specific. Using a pin for that purpose, although less common, it was not an innovation either, that works too. The failure came from the position of the hole and the diameter of the pin, its strength must be put into consideration. Using a needle-like pin on a wood hole near the edge was incorrect. The engineer who designed this specific change obviously ignored that.

Absolutely , poor design.