Couple of questions
 

And I should've asked BEFORE I put the money on the table!! (but better ever than never).

I just ordered 40# recoil spring for my Erfurt, and it comes with the striker spring as well (from Wolff). I noticed that the rear of the toggle is leaving the marks on the frame ("tape test"), and decided to put the stronger spring in it. I am shooting Federal 115gr FMJ RN at 1125fps at the muzzle (I know it's a little hotter than the original Luger load, but not "HOT" by any means). Since the original spring spec. is 38# (I have NO IDEA what/how old is the one in the weapon!), I decided to go a little stronger.

Anyone has the experience with 40# spring willing to share?

Also,.....ordered repro walnut grips from Numrich. Any feedback on those? I know I'll have to fit them to the frame, but how well are they checkered, overal look on the pistol, etc?

I'm aware that the strong springs might cause FTFs, FTCs, and such, and I read that Lugers are "pain" to dial in properly. I just don't want the old thing to get battered.

If someone is using 40# spring, I would appreciate the info on the factory load you are using for the smooth operation (I don't reload, and don't trust anyone's reloads).

Thanks

It's likely that the hard recoil hits relate to the age of the original recoil spring. Replacing them is a good move.

Ensure that you have a good grip with good support when you shoot your Luger. It makes quite a bit of difference for correct cycling.

I generally use the 18-19 coil springs for the WW-I vintage Lugers, and the 21-22 coil springs for the WW-II Mauser Lugers.

Marc

Thanks. I'm familiar with "limp wristing" (I shoot Glocks a LOT). So do you think 40# will work OK in Erfurt?

Every Luger is an "individual". They are spring sensitive, as well as ammo sensitive. The only way you will know if your new spring works out for you is to give it a try. If it short cycles/jams, then you may well want to pop for a lighter spring. These "old girls" are just a trial and error experience to their owners. Good luck.

Daniel,
I bought a set of 3 Wolf springs recently to correct the same issue in my Erfurt shooter as you described it. After removing the old spring I realized that it has significantly shrunk by the time. This was obviously the reason that the breechblock bumped so hard into the rear of the frame. I took the second of the three Wolf springs and it works perfectly with normal ammo out of the box.
Armin.

Yes - there are people that literally wrote the book on spring technology. It's actually a very precision and moderately complex thing...

This write-up is useful for understanding how our Luger recoil springs are designed and work:

http://springipedia.com/compression-stress-spring.asp

The recoil spring in a Luger is called a compression spring. These springs are actually designed to take a "set" when they are installed in an application (like around the guide rod that holds a Luger recoil spring).

Since they are actually designed to take a set, they get shorter than they were when they were manufactured. Once this "set" is taken, they generally do not change dimension again in their lifetime.

The compression principal of a Luger recoil spring is the same as that of the coil suspension springs that hold up a car body. You don't see these lose power and tension over their lifetime unless they are abused (by constantly carrying too heavy a load).

Over the life of the Luger, the requirements for the recoil spring changed as the ammunition, the receiver geometry and the length of the barrel changed. The strength of ammunition ignition and the length of the barrel contribute to the force that the recoil spring must absorb, both in intensity and in pulse shape. Various small changes in the geometry of the Luger receiver also changed spring requirements.

Marc

This is very interesting to say the least. I am VERY familiar with automotive coil springs (used to own two car dealerships in the 90s). And it's absolutely true that they almost never need changing. MY reasoning is,....shock absorbers. They take the pounding, and in return get used up.

IF the gun springs take the set, and never change from that point on, they would never have to be changed. That's not my experience with recoil springs.

This old Erfurt came to me with marks on the back of the frame. I thought,..... OK, smeone shot it with something hot. Then I applied the tape, and shot it with Federal 115gr (that's about as mild as 9mm factory ammo goes these days), and it marked the tape! I realize that this ammo is few FPS faster at the muzzle, than the original Georg's load, but such a little difference should not mark the frame. Since I saw few shooter Lugers without that mark, I concluded that mine has a weak spring (since all shooters I saw used the factory ammo, and not "designer" handloads).

Couple of days ago (when I started this "spring quest"), a friend brought his shooter, and his was not marking with the same ammo. I pulled the springs from both of them, and there was no visible difference between them. I don't have any means of calibrating the springs to actually compare them, and I decided to order 40# spring, and give it another tape test.

Only few things can happen from this point,.......the spring will be too stiff, and I'll have the weapon "short stroking", failure to feed, or failure to eject. Extraction should not be affected, but the short stroke, or failure to eject might cause the stove pipe.

Simple logic tells me that if the weapon goes too far back in recoil,....the recoil spring is too weak. IF the 40# is too strong, I'll have to get the standard 38# spring, or give it a run with some 124gr loads.

I'll report back.

I moved this - sometimes certain parts of the forum are better for questions on repair, etc.

Daniel,

The other variable here is time... Over 100 years, humidity and other things in the air can change metal and it's characteristics through oxidation.

The nature of compression springs includes tensions that vary between the outside surface of the wire and the inner structure. Clearly, it's the outer surface that gets attacked through oxidation.

I suspect that this takes it's toll on very old gun springs like a Luger recoil spring.

Marc

Daniel, you don't say what the tape looked like...Was it just 'kissed' by the toggle, or was the tape mashed flat???

I'm not a big proponent of the tape test. I've attached a pic of three of my Lugers showing the impact area of the rear toggle 'ducktail'...

First is a 1900AE, very pronounced impact area, you can actually feel the depression with your fingernail...Indicative of many years of 'hot' load hammering (or a failed mainspring * )...

Second is a 1937 S/42 [Mauser] with what I consider 'normal' wear...

Third is a refinished commercial which was fired only 10 - 15 times w/'target' loads following the re-blue...

If your frame is close to my second frame then I would not be too concerned about firing Winchester White Box 'target' ammunition in it... :thumbup:

* 1900's have a flat 2-piece mainspring

It is not only the external mark in the rear where the toggle 'kisses' the frame, it is also the internal mark where the breechblock 'kisses' the internal rear of the frame.
Armin

Mine looks like your middle one. Two spots where the blue is gone, no indentation. 40# spring is on the way (cheap!), and we'll see what happens. My pistol also has PRONOUNCED (to the point of the metal deformation) impact areas on both "ramps" (a little more on the left than right). I got the pistol in this state. Both toggle knobs have the blue worn off at the area of the impact. This did not happen with me firing 50 rounds out of it, and it shoots to POA. Next time I fire it, I'll clean the metal with alcohol, and appy the "white out" (the tape kind) on all this, and observe. ANY impact should be easy to see.

I have seen a nice SWISS Luger damaged by a cracked rear toggle from hot ammo combined with a weak spring, so this is a good thing that you are observing and watching for the ammo/spring strength combination!

I run a Wolff #40 in my G date, flawlessy functions all ammo - and I mean all including hollowpoints 105gr through 147gr. But it also did this before I repaced the spring, although I noticed more effort is needed to manually cycle weapon now with new springs.

Also remember, they include an xtra power striker/firing pin spring which help as well. You will notice the extra resistince on lifting the first arm from the breechblock with it installed. It is also far longer then the stocker.

Hi All,

Yes, this is the real problem, when the rear of the breach block, at its most extended position, slaps the upper frame of the pistol. This happens internally, and can not be observed from the outside, unless the pistol is stripped. It can be felt, however, in the web of your hand, if the ammo is hot enough.

When loaded with proper ammo and when the springs are right, this doesn't happen at all.

This is the cause of most Luger mechanical failures!!!

Please don't try to make a Luger into some kind of a "magnum" buy changing out springs, as it won't work, and, eventually, you will destroy your Luger.


Sieger

I wonder if a polyurethane buffer would help on the inside such as other weapons.

I am sure no one here "magnums" their luger with +P, +P+ or NATO rounds. 100 through 147 grain bullets will cause no more excessive recoil then a 115gr round, however the recoil can feel different. German army used 98gr through 124gr depending on load.

Hi,

The German 98gr steel core ammo was not for shooting in pistols.

Please explain what you mean by "the recoil can feel different".

Yes, a lot of hotdogs try to make a magnum out of a 9mm Parabellum cartridge. We actually had one board member that claimed the original German loading was at 1,475 fps out of a 4 inch barrel!!??!!


Sieger


Sieger

Sieger,

1475 is laughable. just like the guys who say you need +P to cycle a luger. I mean the feeling is more of a shove then a flip - if that makes sense.

However my sterling SMG is a different story. Can eat and spit out +P+, 9mm major and double charges like its a treat.

I would never even dream of "magnumizing" the P08. I am very familiar with 9mm cartrige, it's potential, and it's limitations.

I am not as much familiar with P08, but since I collect other "old war relics", I know how to treat them. There is a tool for evey job, and P08 is nice to look at, and shoot once in a while, with mild ammo, close to the original specs. "Tunning" it for +P+ and such, would be like redlining an old engine, and making it the "performance engine".

I never understood the need for increased power in 9mm loads, because I believe in the shot placement (if we are talking about 9mm is SD role). For punching paper, mild 9mm is all one needs. If I "need" more powerfull cartrige, I'll reach for .357 mag, or even 7.62X25. My P08 will be used to scare the wild animals off the property (not to kill them, mind you!), and I haven't yet met a mountain lion that did not take off when he heard a shot. Same thing with deer (need to explain,.....I love to see deer roaming around, however,.....they "steal" the food from my horses, and my dogs want to chase them. The dogs take off, and come back with sprained ankles, cuts, etc. which means more money for the vet. So I try to keep ALL wildlife off the property).

No worries,.....this old P08 will have new springs, repro grips (so the originals can be preserved), and a steady diet of 115FMJ RN.

Interesting thread, I did not know the breech block can slap the inside of the gun if the springs are weak. What sort of wear and tear could you visibly see if this was a problem? Might be a good idea to start checking for such damage before you buy a shooter grade gun!

-Chris