Tuning for Reliability
 

I have a matching and mechanically perfect, albeit bloodstained, 1937 HK Luger that I've been trying to set up as a shooter. So far, reliability has eluded me, notwithstanding the use of Haenel-Schmeisser and MecGar magazines and Wolff springs in all weights, mostly in the form of stovepipes and failures to feed. I would be very grateful for any tuning tips or pointers to gunsmithing literature.

https://lh4.googleusercontent.com/-1...3-no/8551c.jpg

Out of my range experience (mainly with 1911 GLOCKs and CZ) I had stovepipes when my loads were too light fo the recoil spring or the recoil spring too heavy, or problems with the extractor (worn extractor hook, tension too high); I had failure to feed generally when I had faulty magazines, but could be caused also by too much extractor tension, or worse still a barrel somehow throated imroperly.

Sergio

I understand the theory, but in practice my pistol short-strokes on 115 and 124 gr Winchester White Box ammo with a 16 lbs recoil spring, as if it's asking for NATO loads that I'm reluctant to use.

It should work fine with WWBox 115 grs, at least with the original recoil spring. I'm suspecting the extractor might be the culprit.

Michael,

Check to see the condition of the inside chamber surface. If it's severely pitted or frosted from the blood splatter, it might be adding enough friction to the extraction process to put off the timing.

Use some masking tape on the rear of the receiver and look for impressions of the rear toggle hitting it. If there are no marks whatsoever there is not enough recoil force driving things back. If there is too much force (the paper is being hit hard, heavily marked or cut into) the toggle train may be bouncing back very quickly.

Double check how you are supporting the Luger during cycling. You need a firm, solid stable hand hold to oppose the frame recoil force.

Try a 21 or 22 coil recoil spring. This is what was used during later Mauser production and may apply to your HK.

Marc

The pistol is like new internally. There is nothing wrong with the chamber, the rails, or the extractor.

Hi:

Please give us a full definition of "short strokes".

I'm willing to try it again, as your 9mm should work perfectly, with relative ease.


Sieger

Let's make a simple test. Load one round and shoot it. does it lock open?

Can you see any possible flaws to the extractor claws(tips), or the breachface? Does the extractor move freely, and to it's full extent in the extractor channel?

No flaws anywhere to be seen; lock open is sporadic.

Very common to occur. It appears there's nothing wrong with the recoil spring your'e using. You may have some excessive slack in the magazines, it should be no more than 2mm at the bottom.

Nowhere near that much slack in any of the magazines. It feels like the pistol is asking for a spring lighter than 16 lbs, or NATO-spec ammo.

I would use the paper test on the rear of the frame, should be compressed but not broken, this is you optimum cycle.

Stove pipes can happen when the toggle hits the rear of the frame and bounce forward, this increase energy in turn bounces the new round up on the ramp to hard and a jam occurs.

Cycle some dummy rounds through your gun and observe how they get picked up by the breach block and how the extractor slides over the rim of the casing. A rough extractor will cause the new round to tip up as it goes up the ramp and cause a jam

The front of the extractor can be smoothed with 600 grit or higher

Just some ideas :)

Vern

This may be a dumb question, but with the stove pipes and short-stroking I have to wonder do you experience this with any of your other P.08s? If so, you may be limp-wristing it.

The only Lugers I've been able to make work are the LP08 and the 06/29. I never had any luck with the standard P08.

Michael,
Have you verified that the magazine button is not rubbing against the grip, or some other obstruction?
KFS

Mike,

Whatever method you used to make these other two Lugers "work", one of which is a 9mm, should be followed with your new project Luger; as for me, getting my LP-08 to function was a lot trickier than getting my standard model to function. By "function", I mean three shot groups touching and at least 1,000 rounds shot with no jams.

Sieger

I don't have any idea how many P08s that you have tried firing, but if it was more than a couple, and you never could get one of them to function, I would have to consider the shooter. I mean no disrespect, but a very firm grip(one or two handed) is needed to allow the recoil response to fully cycle the toggle train. A soft grip will definitely lead to multiple malfunctions. I speak from experience concerning this.

It may be something totally different than grip, but it is certainly something to consider. The longer barreled Lugers have more sliding mass, which translates to more momentum during the rearward portion of the cycle. That could be making the difference for you.

In a mechanically sound device slow to medium speed burning powder will solve all of your problems. Modern powders are too fast and snappy for P08. Off shelf ammo being loaded with very fast BR powders are not ideal food for P08s. Reason for that is to ensure proper functioning of majority carry weapons on today's USA market. Most of them have pipes less than 10 cm long. Nitrocellulose based powders from the beginning of the 20ieth century were not fast BR powders.

Then maybe you have too little slack on your magazines. Who knows.

I would't recomend the use of a lighter spring, perhaps just the opposite. If the toggle is working too fast there won't be enough time for the next round to present itself in the magazine before the breech block returns.

I understand that. The challenge is to make the gun work with modern factory ammo.

I think the problem is with the feed ramp......when you cycle the Luger manually.....does it feed and eject properly?

I played with this idea in the past, and it has some bases but may not be what your expecting.

A long time a go I had a perfectly functioning luger and as any gunsmith will tell you leaving your gun alone is next to impossible :)

I polished the feed ramp to a mirror smooth surface and then the problems with jams started, it wasn't until several hundred rounds later that it settled down and started functioning properly again.

As a new bullet goes up the ramp, a mirror smooth ramp allows the bullet to float and cause a jam. With some resistance the nose of the bullet is forced down and enters the chamber properly.

Seems strange but very true, lugers are very interesting guns :) :)

Vern

Hi,

What you say here is one of the secrets of getting a Luger to function properly.

Unfortunately, few people know about this, or, if they do, are willing to believe it.


Sieger

That is the problem, then they start playing with springs, modifying them, exchanging them, replacing them. Then they sell it to the next person and fiddling continues.

Only way to modify P08 to digest modern ammo would be to some how magically increase overall mass of the breach or move forward the point where rear toggle link links with 'S' link :). Moving this point forward by even a fraction of a mm would tremendously decrease cycling rate of toggle train.
Increasing or decreasing spring preload will lead only to premature wear and tear of various parts.

Lock Open is Sporadic?
 

With the upper removed, and the sear bar removed does the toggle move smoothly for the full length of its travel? or is there any hesitation or roughness?

Failure to lock open with only one round in the chamber and an empty magazine inserted indicates either a holdopen that has restricted movement (rubbing on the right grip), or that the mainspring force is too heavy. This is the first problem you need to solve before delving into magazine/feeding issues.

1. Check that the magazine button has no rubbing issues at the top of its travel in an empty magazine.

2. Check that the right grip is not preventing the magazine button from moving to the full up position because it is improperly inletted on the inside, or may be slightly oversize on the inside as a bakelite mold error, causing friction and preventing the holdopen from restraining the slide when firing that single round. You can test this by removing the upper and inserting an empty magazine and watching the holdopen. If it hesitates, even a little, it is rubbing the grip. There should be full motion of the holdopen doing this exercise with the right grip removed. The action should be identical with the right grip installed.

3. Install the mainspring from your LP.08 and see how that affects operation. The same results? or not?

4. Obtain an aftermarket mainspring from Wolff that is 16 LBs or less, and start removing approximately a half turn of spring one snip at a time until you are functioning with 115 Winchester White Box. Do this until you achieve lock open 100% of the time.

Anxious to hear how this exercise plays out...:banghead:

I beg to differ. Both my P08s ( BYF 41 and a 1915 DWM) work without problems with current ammo ( Winchester White box; Magtech and Geco) and with my reloads with slower powders (VV N340 and Vectan BA9).
I believe they both still have their original springs.

Sporadic failure to lock open with Winchester ammo is not uncommon. I only had 99% lock open when I used Portuguese military grade ammo.

Another way would be to install adjustable spring. There was a discussion about it while ago. Even patent drawing was provided. Then play with various tensions till desirable outcome is achieved.

I believe you. I had same experience with few P08 myself. Lots of them work flawlessly but topics is about stubborn ones and how to make them work.
Another important aspect is OAL. My experience with WWB is that is not consistent from box to box.

You don't need to increase the mass of the toggle train, provided that a heavy and/or long barrel is in place. An increase in the mass of the canon assembly generally suffices to delay the unlocking of the breech to the point of ensuring reliability.

Portugal being the founding member of NATO, the standing consensus of this forum is to eschew such loads. I am tempted to reinstall the standard recoil spring and give it a go.

Right, but this is not your case judging by pic provided. My idea, was just to illustrate non feasibility of such undertake. We are talking about serious reengineering of ready made product. Keep searching for right ammo combination or get down to proper load and go from there. This will be the starting point with good indications if any other parts will have to be brought up to the right specs.
If you decide to go with heavier barrel you will be opening whole new can of worms.

I agree you should give it a try. It was going to be my next suggestion anyway.:D

Hi,

For a perfect fast powder target load, that works every time, try the following:

WW Commercial Cases
Remington 1 1/2 Primers
Hornady 124 gr FMJRN
Bullseye 3.7 grains
Cartridge Overall Length 1.173 inches

This is a fantastic target load, but it is a light one, less than 1,000 fps. On normal occasions, with hand held over a sandbag, up to seven have touched on a 25 yard target.

If you HAVE TO shoot fast powder, this load is an excellent one to use. Higher powder charges with this powder will cause both wider groups and cause jams.

The Winchester White Box, for me anyway, is not accurate in a Luger, as it throws bullets all over the paper at 25 yards, whereas, my carefully crafted handloads will put all eight in the 10 ring at 25 yards. Please search this section for a full listing of my most accurate handloads, if you like.

Just some of my experience with fast powders in a Luger.


Sieger

Hi,

I don't know what the Europeans are loading as NATO Spec. ammo, but according to our government's official publications on the matter, we are loading a 121 grain bullet to 1,260 fps. (as shot through a pistol)

According to extensive research I have done, in both German commercial and military publications of the period, the original WWII German 9mm Pistol ammo was loaded as follows: 123 grain bullet to 1,076 fps. (as shot through a pistol)

Just do the math. The U.S. NATO Spec. loading is overloaded by approximately 184 fps or 17%. Though this is not a perfect comparison, I think we can all agree that more "energy" is needed to throw approximately the same weight bullet 184 fps faster.

The implied conclusion, from these facts, is that one shouldn't need ammo overloaded by some 17% to get a Luger to function properly (with an original set of springs, in spec., anyway).

Your thoughts?


Sieger

I avoid reloading with fast powders. Exception .32 wadcutter

There's a trick to WWBox. You have to sort them out by weight.
Proof. Competition target 25 meters one hand shooting
Attachment 43858

Hi,

I had no idea that Portugal was the founder of NATO, as they didn't even participate in WWII.


Sieger

I don't know what is being made all over Europe as NATO SPEC 9mm.

Portuguese loads (no longer available since the Government shut down the facilities around 2005) used 115 grain bullet at, if memory serves me right, around 1240 1280 fps.

I would not shoot 121 grain bullets at 1260 fps from my P08 either.

Hi,

You may not reload with fast powders, but if your shooting White Box, you certainly are shooting it.

Well, whatever "sorting" you are doing with White Box, apparently, seems to be working for you!

Good shooting!!!


Sieger