1900 AE Heavy Wear Marks?

[Karl]

I have a 1900 AE shooter and have been following this thread with interest. I use reduced loads with light bullets in an effort to prevent damage. Regarding the method of measuring spring tension:
Would it not be more accurate and consistant to measure by inserting a soft aluminum or brass rod in the barrel and measure by pushing it against a scale?
KFS

[sheepherder]

Originally Posted by ithacaartist

Glenn,

I think postino's talking about two different methods, and the one with the gun at that angle in the pic would be for the scale/meter thing he's pulling it with. Loops of string around the toggle knobs and a weight that can be varied on the other end would be an entirely second method--and I think when he says barrel pointing up, it means straight up. You'd be hanging onto the barrel and dangling the weights from the toggle knobs until they rack back to the limit of the cycle. This way, gravity is doing its thing at the same angle you'd apply the force to draw the toggle back, relative to the pistol itself. One could use a fish scale or similar, one end fastened to the floor, in line with the toggle strings. Loop the loops, pull up on the barrel, and take note of the reading on the scale when the toggle moves all the way back. I guess you could do this in a horizontal setup, too; but make sure it all lines up the same way as the dead weight setup...or clamp the barrel in a padded vise and pull on the far end of the scale, etc. etc.

Yes.

Originally Posted by Karl

I have a 1900 AE shooter and have been following this thread with interest. I use reduced loads with light bullets in an effort to prevent damage. Regarding the method of measuring spring tension:
Would it not be more accurate and consistant to measure by inserting a soft aluminum or brass rod in the barrel and measure by pushing it against a scale?
KFS

Sounds good to me! I don't have a scale.

[skeeter4206]

OK heres my new update on my data. I got a digital fish scale and put an aluminum tie wire on the end to wrap around the toggle in the same location that Postino did. I clamped the grip of my gun to were the fron portion of ht egrip was at the 90 degree orientation from the table. Trying to pull with the scale parallel to the table as much as possible. I left an empty magazine in the gun so a had a stopping point once it clicked in the open position. My readings averaged around 10.5 to 11 lbs just before it cicked into the open position for the toggle.

[sheepherder]

Originally Posted by skeeter4206

My readings averaged around 10.5 to 11 lbs just before it cicked into the open position for the toggle.

Excellent!

Should we start a chart???

Or maybe a poll???

(You should not attach any significance to the angle of the Luger...I did it that way to get a good camera shot...And that was where the flats of the gripframe were...)

[Dwight Gruber]

I'd be interested in knowing the rate of tensioning of an old-model flat spring and a new-model coil spring.

--Dwight

[sheepherder]

Originally Posted by Karl

Would it not be more accurate and consistant to measure by inserting a soft aluminum or brass rod in the barrel and measure by pushing it against a scale?
KFS

I don't have a scale or a 30 cal squib rod long enough, so I tried a 1/4" wood dowel and my mechanical spring scale...It doesn't work...There is too much friction from the dowel sliding down the barrel...I got wildly erratic results, up to 16 pounds...(first pic below)...The pull was very 'jerky'...

If you're doing the rod in barrel 'push' method using a postal or bathroom scale, remember that those are 'zeroed' using gravity as a constant...If you use these, put the scale on the floor and push down against it...(Not from the side)...But I think friction would still affect the results...

Originally Posted by Dwight Gruber

I'd be interested in knowing the rate of tensioning of an old-model flat spring and a new-model coil spring.

--Dwight

Good idea; I re-tried the 1900 AE w/flat spring held in soft vise by the trigger guard, and then the 1937 S/42 coil spring held the same way...(second and third pics)...I got pretty much the same spring tension at full toggle travel; 10 - 10 1/2 pounds for the S/42...

I straightened out the clamping [no angle] so y'all wouldn't get so confused...It made the pic bigger...And I left the magazines out...

Interesting comment: Although the final spring value was essentially the same between the flat vs coil spring, the 'feeling' of pulling the toggle back was markedly different...I can't really describe it, except to say that if I was blindfolded, I would be able to tell which pistol was which by the spring pull...

[skeeter4206]

Well postino I got to agree with you. I took my other luger this morning with a coil type mainspring and I also got right around 10.5 almost 11. But it takes a more of an initial pull to get the toggle to start moving. Once It passes a certain point and start pulling slowly to the point where the hold open catch catches, it reades almost the same as my 1900. Weird cause I sure though it would be a much higher reading. I think its just that initial point of getting the spring to start compressing that just feels totally different that the leaf spring that doesnt have that kind of action.

[sheepherder]

Originally Posted by skeeter4206

Weird cause I sure though it would be a much higher reading...

The coil spring Luger has a "L" shaped 'recoil lever' between the coupling link and the mainspring which the flat spring Luger does not have. I think this changes the feel of the pull...It may even provide a mechanical advantage by providing leverage that the flat spring does not enjoy...

It's been 37 years since I took all this stuff in college, and trying to plot vector diagrams to determine mechanical advantage is beyond me...

IIRC, springs are rated by the amount of weight required to compress a spring one inch...So a 36 pound mainspring should take 36 pounds to compress it one inch...

I was mildly interested in seeing how much pressure it would take to deflect the flat spring one inch...(Pic attached)...

It took 6 pounds...Unfortunately, this has no relation to anything in the real world as pertains to this discussion, as the Luger grip frame has several points that touch the mainspring and affect the mechanical advantage...

But it does give me a base to compare other mainsprings against...Without installing them...

I have been told that some gunsmiths have made replacement flat springs by milling a single piece of spring steel to the required size & shape...It would be interesting to compare those with the OEM two piece Luger mainspring readings as detailed in this thread...