Mainspring question follow-up for GT

[DonVoigt]

In reference to your earlier thread:
http://forum.lugerforum.com/showthread.php?t=34217

What were/are the size and turn specs on the spring you replaced the "faulty" one with?

I'm having trouble with the logic of so many "mainspring varieties"
shown!

Seems to me the MS can have an effect on the hold open performance in two ways:

1- if too weak, the toggle may rebound too far and bounce
back, overriding the hold open before it rises

2- if too strong, it is not allowing the toggle to raise fully and retract
sufficiently for the hold open to rise and catch the bolt.

I suppose not only the "strength" but also the length of the spring
enters into the performance equation.

Any comments/ ideas?

Do you think you put in a "stronger" spring ? or a weaker one?

[DonVoigt]

Remembered I just received a Wolf main spring "tune" kit this week.

Each spring is packed individually , so I took them out one at a time and measured:

Nominal Strength All in Inches
by Wolf definition Free Length Wire size O.D. # Turns

36 3.40 0.056 0.393 19

38 3.64 0.056 0.393 19.5

40 3.50 0.056 0.093 19


"extra strenght"
striker spring 2.30 0.028 0.023 18.5

I have no way to determine the compression strenth; but it is
fairly clear the Wolf rating is not at "full compression" in the referenced Luger table, where weights are in the 50-60 lb. range.

I can't explain why the progression from 36, 38, 40 seems out of line, essentially like they mis-labeled the 38 and 40 # springs!

I will email/ call Wolf Monday and ask them!

GT,
I assume, maybe shouldn't, that you used the same ammo when
testing each spring? Could you confirm and also tell us which
ammo you used.

From my other post detailing the hold open vs. ammo, it is clear that any given spring/mag/ammo combination will behave differently. Well, at least it is clear to me.

Check out the firing results starting at post # 16, in this thread:
http://forum.lugerforum.com/showthread.php?t=34250

[4 Scale]

Don the Luger mainspring G.T. was referring to was in a Luger he was working on for me, trying to improve the hold-open. Initially, hold open worked only 75% of the time on last round. He and I sent pistol parts, a complete pistol, and magazines back and forth for several weeks.

We were stuck for awhile; finally he tried a new MecGar that seemed to push the hold open up just a little higher. That, and a slightly weaker mainspring, resulted in perfect hold-open function.

The pistol was "weird". A '38 frame with a replacement Mauser-proofed barrel. The receiver had been marred externally by whoever replaced the barrel; we think they likely twisted or somehow altered the receiver geometry and that put some drag on the toggle action. I.e., at least part of the problem seemed to be, the breech bolt was not traveling far enough on recoil to engage the hold-open. We deduce that because cutting coils of the mainspring improved hold-open reliablity.

If G.T. hadn't thought to try that new MecGar, we'd still be messing with the mainspring. Or given up, it was a very long story and I'm leaving out a lot. I just wanted to let you know, the fix seemed to be the combination of slightly weaker mainspring and a new MecGar. One way to get a slightly weaker mainspring is to cut off 1/2 coil at a time and test. We also used tape on the back of the receiver to see if the toggle was striking the receiver - sometimes it was, sometimes it wasn't.

Per your specific question, we used 115 gr. WWB exclusively. I had heard that Lugers can be finicky about magazines, that not all magazines work correctly with all Lugers. Boy is that ever true.

Fortunately for me G.T. has the patience of a saint and (like me) enjoys the thrill of getting recalcitrant Lugers to function correctly. Without his help I doubt the pistol would run perfectly like it does now. Pending G.T.'s comments, that is my 2 cents.

[sheepherder]

Originally Posted by 4 Scale

The receiver had been...twisted or somehow altered the receiver geometry and that put some drag on the toggle action...

I've run into a couple like that. You can check with a pair of spirit levels like the pic below. This one had a twist and the toggle dragged.

There's a pic in the Barrel Replacement thread of a brass block that is inserted in the receiver to eliminate any twist when removing the barrel.

http://forum.lugerforum.com/showthread.php?t=25418

[4 Scale]

Thanks I'll play with it some and see if I can learn anything with that method, I'm still curious about the receiver condition. G.T. did do some work on the receiver, hopefully he will comment here.

[DonVoigt]

4 scale,
Like so many semi-auto pistols, some like one brand/type ammo and not another; also two identical appearing mags do not necessarily work the same- as both of us have found out.

You possibly could have also "solved" the problem with an ammo change.

I have a standing rule at the shop where I do a little 'smithing, if it doesn't work correctly- bring the ammo you are using! No ammo, I don't waste my time trying to fix it!

[G.T.]

Hi Don & 4 scale! I just now saw this thread! And 4 scale has pretty much described the issue and cure as it came to be! This particular Luger was as hard to diagnose as I believer they will ever come?... But we just kept testing, tuning, and trying until we were satisfied with the reliability level desired... The springs in the chart are all over the place, but I think one would find very similar compression rates at a certain point of deflection?... As both wire dia. and number of coils plays a part in it's performance... I only use WW target 115 grain ball in every test, every time...... Lugers were mass produced, but not necessarily made with 100% interchangeable parts..it makes testing hard, because you can't always switch out components and get the results you expect or desire??? That gun was a lot of fun to try and solve... I think we did pretty good with it.... ... Best to all, til...lat'r....GT