Baby Luger Breech Block Slap

[milesc2]

I was inspecting my baby Luger after my first range trip with it and discovered that the breech block had been hitting the inside rear of the frame.

The damage was minimal and I was able to clean it up pretty well with some light sanding.

To try to resolve this issue I installed a longer mainspring. I believe it now has the longest possible mainspring installed. (any more and the action would not cycle enough to engage the hold open)

It seems the issue is MUCH better now but after firing about 130 rounds I can see a small amount of breech impact on the left side of the frame. It is very slight compared to before but I don't think these surfaces should be touching at all.
I dismantled the pistol several times while shooting and it appears the mark was not getting worse it was there after the first couple mags and stayed the same as far as I could tell.

I am using regular Winchester white box 9mm Luger 115 grain.
I see no galling, wear or damage on another part of the pistol.
The gun passes the tape test just fine.

My questions:
Is this amount of impact normal? Will it cause issues down the road?
Why would the left side be the only one getting hit?
If need be what can be done to correct the issue?

First photo shows the frame after I cleaned up the original damage.

Second photo shows the frame after 130 or so rounds fired.

[Sieger]

Hi,

Who's baby is it?

Slap can be traced to too hot of ammo, or too weak of recoil spring.

Original Lugers, with proper ammo, did not slap; as this is the primary cause of mechanical failure of this system.

Sieger

[milesc2]

I just don’t see what other options are as far as springs and ammo goes.
Is there some special type of spring used in the baby Luger?
The builder of this pisol is more than willing to help me resolve this issue he just has not seen this on any other builds of his. I doubt most of his customers fire the babys as much as me.

I guess this is going to require some sort of double recoil spring setup.
Surely someone else has run into this issue?

[hayhugh]

The builder of this pistol is the man to resolve this issue..........

[G.T.]

Take the baby luger mainspring out, and with the unit unloaded and grips off, pull the toggle all the way back until the rear toggle stop touches the frame... Measure the distance between the end of the spring guide and the bottom of the frame spring stop web, at the top of the spring area..... Now, take your main spring that you are going to modify, and using a drill bit the fits in the inside of the spring, drill a hole in a piece of aluminum or plastic and using the hole, drill and drill press as a tool fixture, completely compress the spring to solid!! Measure, and grind some off, repeat until the compressed spring will fit in the area left on the spring guide at full recoil... .. install and test! ...best to all, til...lat'r....GT

[DonVoigt]

Miles,
remember you are dealing with a piece that was not "designed" for high volume shooting!
It is an alteration that shortens the space available for the mainspring.\

Theoretically the shorter spring should be the same strength as the long one, but there is not room- so the diameter of the wire would have to be increased slightly, again theoretically.

Since many lugers show some contact at the rear, I'd say it is acceptable, if not "normal".

Practical advice, don't shoot it so much that it causes the problem!

PS- Your MCC gage is done and ready!

[Rick W.]

As a casual reserver, I am not quite convinced that shortening an oem spring is the real answer to some of these issues. I am aware of several converted Lugers that work just fine, but always think there is better over the hill sorta speak.

I heard that some custom springs were made up a while back for these 7 shot conversions, hard for me to call them "baby" as the 7 shot version does not look like the originals, but just my opinion. It might be interesting to research, if available, what went into these specialized springs.

I wonder if one of the rear frame surfaces is further ahead than the other? Or does the extra show up on the rear toggle itself? Blacken the area of concern with a candle, reassemble and shoot a few more, the number of rounds is up to you. If you dressed the marks down, do they still appear as before? Just an easy observation to try, does not cost much in the attempt. One would suspect some tolerancing in the frame surfaces, or whatever over the last 100 years.

I often wondered what Werle across the big pond used in his cut down Lugers; spring wise, some were really short in barrel length; suspect he did both calibers of 9 and 30, but just a guess on my part. If he is still around, a query might be helpful. If he is retiring, well, that was that, we are on our own.

Over the years, I have come to like a slower than recommended powder in the Luger, kinda gives the mechanism more time to ponder its operation, rather than just slamming around. Bullet weight comes into play at times as well. If one is stuck with factory ammo, then the whitebox is not a bad choice in my opinion; no real experience here in oem ammo, haven't bought any for 40 years. Never thought of the 9mm for qualification really.

Getting a spring made up for these 7 shot conversions is probably cost prohibitive, other than doing it yourself; the quantities for sale would not be too heavy probably, never recoup the R&D costs. My time is worthless really, but do not have the springy expertise yet; does sound interesting but time can be short.

[milesc2]

Thanks for all the advice everyone!

GT: I believe I am at max spring length as it sits. I was fitting the spring then clipping 1 coil and installing it again. I think if I do your procedure I will end up with a spring about half a coil shorther than the one I have installed. I will give it a go though once I get more springs. They are too cheap not to try, maybe I can get an extra 1/4 coil in there?

Don: I don’t plan on shooting it this much. I was more or less testing if the wear on the frame would increase after each shot.
I know it was not designed for this type of shooting and after I get it running right I will shoot it much less.
You say this impact is somewhat normal? I have not seen many examples that show this wear. (Haven’t seen enough Lugers taken down)
I’m not sure how hard it is actually hitting the frame. Just trying to decide what this impact would eventually lead to down the road. Frame crack?
Does your baby show any deformation in this area on the frame?


I think the answer may be some sort of double spring setup. A smaller diameter spring that sits inside the mainspring?
Has anyone heard of anybody developing something like this?

As suggested I’ll send a note to Mr. Wherle as well.

[milesc2]

Rick,

Thanks for your advice. I’ll do my best to answer your questions:
I dressed the area down after the initial damage. Then fired a lot of rounds and only see the slight impact mark show. I have not dressed it down again and here’s why:
It almost looks to me like the left inside of the frame (the side getting hit) is (maybe) slightly farther back than the right side. I have no way to measure this and it does not seem to match the wear pattern I am getting.
I would love to test removing a little metal on each side but would hate to do that needlessly so I’ll hold off.
I agree with you that the regular trimmed coil spring is not the best option here.
How could a trimmed spring ever be as strong as an OEM length one?
Either a wire diameter increase or a double spring is needed in my opinion and I’m not convinced that a larger diameter wire would resolve it either.

[milesc2]

This is similar to what I have in mind:
1911 with double recoil springs.

Would anyone know where I could find a spring that would fit inside the mainspring to test?

[ithacaartist]

If the ID of an original spring allows enough room between it and the guide for enough of an effective spring, this might work. If not, it sounds as if you'd need two custom springs--one for the inside helper, and another main spring that will fit around it.

[DonVoigt]

Miles,
Since I built my "7shot" baby myself, I have been down this road. A few observations
that may help :
-there is not enough room for a double spring
-a shortened spring is just as "strong", but lacks the tension at the end of the stroke for closing
-all springs are not the same, I was fortunate enough to have a handfull of old, take off, or out springs to experiment with.
-You will just have to "play" with the spring/ammo combination; but it sounds like what you have is working well
-Yes, some impact at the rear is normal- I have seen it in many/most lugers and have seen many that are quite a bit worse than yours.

Short answer, if it feeds and cycles now, leave it alone; and don't stress over a little impact!

You could show a picture of the back of the frame where the toggle bears against the frame. This will help understand if the spring is really weak, or you have a parts length/space mismatch inside.

[milesc2]

Don,

I think leaving it as is may be the best answer yet. Your right about the double spring setup. I just tried to make one with a C96 mainspring and came very close but there just wasn’t enough room.
Also did GT’s measurement test and have confirmed it’s the longest possible spring that can be installed.

Your last point got me thinking... Could a small amount of material be removed from the back of the breech block? It seems as if the parts coming into contact are hitting very slightly, just enough to leave a mark. Maybe if a little material was removed they wouldn’t touch?

I am not removing it myself again... It was a miracle I got it back together without scratching anything!!!

Here are the requested photos. Please ignore the fingerprints.

Best,
-Miles

[G.T.]

Hi Miles! Hey, you might have an interference issue in that it is impacting inside while not reaching the stop on the rear toggle outside? check it without the mainspring for travel and clearance?
On the mainspring... there are many different wire diameter variations right in the Luger mainspring family! I've seen them from .0535" all the way to .0685" and I'm not sure what the Wolf springs are at the moment! But, if you haven't an interference issue, then you need to measure the main spring wire size and go up a few thousands, with all else being relatively equal, you should be able to cure the issue?... ... I have some used take out springs that you can have to play with, just need to know wire dia. so we have a benchmark to start with?.... best to all, and Hi Don & Rick .... With these two guys on the hunt, and picking up the scent, the best dogs are definitely running!! best to all, til....lat'r....GT

[DonVoigt]

Seriously,
it is not an "issue"!

It is clear, at least to me, that most of the "stopping" or contact is occurring at the toggle/rear frame outside interface.

There are at least three areas that could "touch", the outside rear frame, the inside area shown in the first picture, and the round circle most often seen where the firing pin guide contacts the rear.

Remove the contact at one point, and it will likely move to the next. JMHO.

[milesc2]

Gerald,

I am starting to think this is over my head. I don't have the skill to be working on this gun myself.
I was barely able to get the longer mainspring installed and I don't want to risk damaging or scratching the pistol. It's just too expensive for my unskilled hands.

I'm not sure exactly how to "check it without the mainspring for travel and clearance".
I could unhook the mainspring to do the testing but I'm unsure of the steps involved for the test you speak of. Really don't want to remove that spring again myself.

Also unfortunately I don't have anything accurate enough to measure the diameter of the wire.
I believe I purchased it from Wolff within the last year. I can search for the specs of their springs I guess.

This pistol may need to go back to the builder for fine tuning if anything else needs to be done to it. I just want to make sure firing this pistol will not cause any further damage. I am leaning towards Don's solution at this point but would like others to chime in as well. I just don't know enough about breech impact to make the call.

Thanks for the offer on the springs.

Best,
-Miles

[G.T.]

Hi Miles, I think you are wise to not try to much if you are not familiar with the task or the trouble!
I do know that at the end of the day, a gun that is correctly tuned shouldn't beat it's self like a midget with a hammer? ......And, that springs don't get stronger! ... (probably why contact is happening now? Spring has taken a light set?) If you do decide, at sometime in the future, to address the spring, start with a spring too strong and go from there?... (won't lock open, etc.).... best of luck on the task, and I know that Art was probably very close at the outset and perhaps a small adjustment will make a world of difference... best to all, til...lat'r....GT

[milesc2]

I’ll have the builder look at it when he has the time.
I won’t fire it anymore until he gives the go ahead.

Thanks for the advice everyone!

[milesc2]

Just looked at Wolf's web page again and have a question:
They list 3 different spring weights: 36, 38, and 40.
I am using a cut down 38 at the moment.

Is the 40LB spring made out of a thicker wire or just longer spring?

[Rick W.]

Miles,

When I referred to surfaces possibly being unequal, I was mainly referring to the the interior frame surfaces in your picture, the red arrow pointing to a mark.

I see that you are aware of the tape routine at the rear of the Luger. Someone here mentioned such years ago, someone had a piece of brain I reckon, a simple and easily read diagnostic. Every now and then on this forum, there is an elegant piece of information for the shooter that stands out.

A few of us here, have delved more deeply into the Lugers from a mechanical and functional point of view. Not much of a badge of honor or meant as imitation; just that we have the curiosity and are willing to take responsibility for our mistakes in learning on our own. An in the flesh mentor is worth his weight in gold, but not many have that privilege. There is nothing that one cannot learn, if you take the time and effort to do so, by whatever means. Just a bit of encouragement.

From what little I know about the issue you presented, the pictures do not really present much of an issue. A lot of Lugers will give a light touch at the rear, I try to get rid of such myself, with various approaches, but only one opinion in the many. Everyone likes to think for themselves you know.

Some of the rashly purchased Lugers that I got over the years, the first time I put rounds through them, I noticed a sting in the hands from the grip. There were ones with very weak recoil springs; so one might consider using one's sense of touch. If it is just kinda soft recoiling feel during operation, probably all is in pretty good shape. If you get a stinger, something is amiss, possibly the recoil spring or ammo power. The Luger will function for quite a while with a lot of abuse really, for a 100 year old design, tis not so bad. As we get older, we all seem to need an little extra care......

Rick W.