Opinions on Sideplate Fitting ?

[sheepherder]

I'm asking for opinions on fitting a non-OEM sideplate to a mixmaster Luger.

Here's what I have so far:

- Mixmaster Luger w/humpback Mauser frame, Sarco repro artillery barrel, all-Mauser upper
- Assortment of sideplates with various problems

Some of the sideplates have bent front tangs [red circle]; some have too-thick rear tabs [blue circle]; some have too-thick front tangs...

The Mauser on top has a sideplate that is a perfect fit on the faux arty...Unfortunately, it is a perfect fit on that Luger as well...

What is your method of fitting??? Do you bend or file the front tang to get it to fit??? Do you file/mill the rear tab to get that to fit??? (The rear tab on the 'long-humped' sideplates are .005"-.007" too thick for the frame slot).

In my mind, the sideplate with the too-thick front tang is the easiest to fit...It just needs a little filing to let the takedown lever fully engage...

...But is that the 'right' way to fit a sideplate???

[Diver6106]

I bought one of the cheaper repro cast plates (like the one on the left side?) and had to file down both of these spots and the top rail. I definitely would not file the other parts of the Luger. I took off just a little at a time and insured it fit well. And was very careful to insure the geometry of the indent that takes in the trigger pin and the trigger lever clearance was not effected.

[John Sabato]

The rear tab should be a "perfect" fit or as close as you can get it by polishing the tab until it will enter the slot without much resistance. The front tab if too thick should be polished on the underside until the takedown lever will close, again "without much resistance. It is a "feel" kind of thing. The sideplate when fitted properly should not "float" between those two points. If it does, you will never get a consistent trigger pull.

The curve on the front of the sideplate should be a matched fit to the diameter of the takedown lever.

Now you know why these pieces were numbered to the gun when they left the factory. Other "may" fit, but only the original parts were manufactured to fit when the gun was presented for the final acceptance inspection.
You said that you had a sideplate and a Luger that were a perfect fit... use it as your control when polishing the new sideplate. They should feel pretty much the same when fitting is completed.

In addition, the hole in the trigger lever should be a good polished fit to the pin that holds it. If it is a sloppy fit, then again, the trigger pull will never be consistent, but will vary as the sloppy lever gets pulled down by the trigger. Polish all bearing surfaces of the trigger lever (not metal removal mind you, just polishing where the pieces may drag when rubbing against each other.)

The result should be a reasonably good trigger pull.

[sheepherder]

Originally Posted by John Sabato

The front tab if too thick should be polished on the underside until the takedown lever will close...

What is the rationale for the underside being polished (I assume you mean filed/sanded)??? I would think that if the trigger worked OK that 'polishing' the topside, where the takedown lever rubs, would be the correct area to 'polish' (in fact that was my intention). What am I missing here???

'Polishing' the underside would, it seems to me, bring the entire sideplate assembly closer to the frame. May require filing the notch for the frame, deepening the trigger shaft relief, etc.

Each sideplate does not have all the problem areas mentioned. One has a bent front tang, another two have thick rear tabs, one has the thick front tang. Of these, the one with the thick front tang seems easiest to 'fix'.

Is it safe to bend the front tang??? Will it bend or break??? If the front tang is too short what does that do???

[DonVoigt]

In kind of reverse order, if the front tang is too short, the side plate will be loose- with fore and aft movement.

I would not try to "bend" the tang, it might break and it would not fit correctly if "angled"; but of course you have one that is already bent, so nothing lost if you try to straighten it. Holding it without causing more damage will be a challenge.

Actually both sides of the tang should be fit, the back should fit the curve of the frame and lay flat against it. Then the front can be filed to allow the locking arm to close, use prussian blue to find the high spot(s). In the literature there is a spec. shown for the "extra" thickness left on armorers
replacement side plates, I don't remember where but perhaps 0.1-0.2mm was left for fitting.

The fit of the arm to the curve of the tab should be done concurrently with the fitting of the top of the tang, they should allow the arm to rotate snugly against the side plate and be tight in both areas when fully "closed".

The tab into the frame is probably the easiest to fix, just adjust the thickness with a fine safe edge file.

Hope this helps.

[mrerick]

The thing that can deliver consistency to trigger pull on a Luger is the flatness of the trigger plate against the receiver. The pressure applied by the take-down lever (in closed position) and the catch at the rear edge of the plate must be exact and uniform. Anything that allows rocking or movement against the side of the receiver will lead to inconsistency in the trigger.

Again, precision flatness of the fit with uniform pressure preventing movement of the plate against the side of the receiver is your goal. That's why you work the back of the trigger plate.

One good thing about having one plate that fits it precisely is that you can transfer and check measurements between them.

Marc

[sheepherder]

OK, my apprehension about polishing/filing/'fitting' the rear of the sideplate stems from the process of moving the centerline of the trigger lever closer to the frame/sear. Because of the 90º shape of this lever, this can affect the sear engagement.

I don't have an armorer's oversize sideplate, although one of those [maybe two] shown above are aftermarket pieces and may be oversize. But the sideplate with the too-thick front tang seems most promising.

While I understand that trigger pull is important to some shooters, right now I just want to get the plate fitted. I'll adjust for pull later.

The length of the front tang [where it hits the takedown lever] hadn't occurred to me (I was more concerned about thickness). I'll check that today.

Ed Tinker also commented that the takedown lever affects the sideplate fit. I don't have but one of those. Something for me to look for.

Always good to get a number of opinions and justifications on a subject I know nothing about. I thank you all!

[sheepherder]

My cannon assembly was very tight fitting to my frame, so last night I stripped the frame down and lapped in the barrel extension. It turned out quite smooth. I cleaned the lapping media off with solvent and scrubbed the parts with a stiff brush and soapy water, then blew the parts dry with compressed air.

This is how the 'thick tang' sideplate fits. The takedown lever is sloppier than I would like (side-to-side) in it's cavity, but it's what I gots.

I don't want to force the lever up any more than I can move it with my thumb. As is, I have to move it down with a clothespin half to get it disengaged.

[Ron Wood]

Where did you get that takedown lever? It could be just the angle at which the photo was taken but it appears that the lever is too long and is bumping into the side plate before it can be fully rotated into place.

[DonVoigt]

Originally Posted by Ron Wood

Where did you get that takedown lever? It could be just the angle at which the photo was taken but it appears that the lever is too long and is bumping into the side plate before it can be fully rotated into place.

I believe you may be right, looks like contact at that angle to me too.

I have had this problem, one can reduce the front edge of the side plate if the interference is only a "smidge"(that's a tech term for not too much"?

Better solution is another side plate, or lever.

I go for another lever is that one is loose side to side, JMHO.

[sheepherder]

Originally Posted by Ron Wood

Where did you get that takedown lever?

It came with and is numbered to the pistol.

It could be just the angle at which the photo was taken...

Yes, exactly. New closeup pic attached.

Originally Posted by DonVoigt

I believe you may be right, looks like contact at that angle to me too.

You both need glasses.

[DonVoigt]

Originally Posted by sheepherder

It came with and is numbered to the pistol.



Yes, exactly. New closeup pic attached.



You both need glasses.

Got glasses, what you need are better pictures!
Just trying to help, no more.

[Ron Wood]

Got glasses, etc., etc.

[aldo35]

I had the same problem when trying to fit another locking bolt to a shooter. I solved the problem by carefully removing metal from the tip of the side plate that engages the locking bolt with a file and a sharpening tone. It took several attempts to achieve the closure.

Aldo35

[mrerick]

With the parts removed from the pistol, consider wrapping the takedown lever itself with very fine emery cloth (grit out) and using it to slowly and carefully shape / polish the curved end of the side plate tab. That way you retain the proper shape for the curve. Prussian blue as indicator pf metal removal and of proper contact...

[sheepherder]

Originally Posted by John Sabato

The front tab if too thick should be polished on the underside until the takedown lever will close...

Out of the several opinions offered, John's seems to be the most reasonable...So here goes...

I draw filed the rear of the sideplate with a fine mill file; progressively sanded it with 220/320/400 grit wet/dry sandpaper; polish with emery cloth; trial fit to Luger...Repeat as needed...Until takedown lever would rotate into locked position.

The sideplate from my other Mauser Luger fit & worked quite well, and on mic'ing the front tang it measured .097" thick. The tang on the #47 sideplate measured .099". So it was only off by ~.002".

I'll assemble it all tomorrow. I'm missing a takedown lever retaining spring and an artillery rear sight base spring (the flat one) but otherwise finished assembling an artillery shooter.

[DonVoigt]

What I wrote was not "opinion", I have fitted three side plates in the last 6 months; and was just trying to save you the time it takes to learn it all by yourself. Each was a little different and required tweaking in one area or two of the three you identified.

[sheepherder]

All knowledge is valuable, everything gets noted. Some solutions are obvious, others not so much.

Thanks again for all your comments!

(Sideplate shown here on the rarely-seen 1942 Mauser Cartridge Counter Artillery Luger)...

[mrerick]

Nice work Rich...

Watch out, or a certain dealer with a colorful and wordy website will want to sell your one of a kind "variation"!

How does the trigger feel?

Marc

[sheepherder]

Originally Posted by mrerick

Nice work Rich...

Watch out, or a certain dealer with a colorful and wordy website will want to sell your one of a kind "variation"!

How does the trigger feel?

Marc

Ooh, I didn't know he had a website! He's 70 now, I imagine he must have some younger apprentices working for him...

I think I can come up with a 'war story' that would explain this exciting and rare variation...I think it was issued to the long-range Focke-Wulf Condor pilots [from KG200] who planned to bomb New York City by refueling on ice floes in mid-Atlantic with avgas supplied by U-boat...

Trigger doesn't feel too bad, but my experience with Luger triggers is limited. I know enough not to compare them to anything else, but if I think of it I'll test the pull against my other...three?...And see how it compares...

The trigger spring I had been using went into coil bind before releasing; I had a shorter one in my spares that 'fixed' that particular issue...

The mainspring did seem longer than the three or four 'spares' I have in my parts box...