When you feel like it, please measure the wire size , # of turns, and free length of the springs you received.

Some where I have a post with that info, I'll have to find it (again), for comparison.

I will do that for the one that came in the gun and the 40 pounder today after I get back from the range. I am in no hurry to remove and replace the one that is now in the gun, as even with my homemade special tool it's a pain. I can give you a coil count and maybe a wire diameter measured in place. Actually, if I removed the spring and measured its length, it would probably be misleading. Even after a few compressions a spring like that will be shorter than in its virgin state.

I'm not sure that coil count and wire diameter will tell you the whole story. You also have to consider steel composition and heat treatment. For example, the replacement "extra power" extractor spring from Wolff is significantly smaller in diameter and length, and has less coils than what was in the gun. Only the wire is a bit thicker. At first I thought it must be a warehouse picking mistake, as it's a bit of a loose fit going in. But after installing it I find that it is indeed stronger.

The 36 pound spring, which gave me flawless reliability with all ammo tried, has wire that is .055" in diameter. It has 21 coils. The 38 pound spring has the same, and is 3.625" long.

Sounds like your pistol no longer had the original spring.
Thanks for the data.

I'm pretty sure that Wolf uses the same spring wire for all the luger mainsprings.

Anyway- it is good that the new spring fixed your problem!!!!

Glad to hear that you found the "magic combo" and have good reliability with factory and handload ammo. Lugers are sooooo much more fun to shoot when the run reliably.....actually, I guess, any gun would be that way...Duh!!