Stevie,
Lugers were built to operate with hotter ammo than todays American ammunition. That is why you had to go to a lighter spring to get reliable function. You can try the 38# spring, but that is probably equivalent to the original spring. If you get malfunctions, go back to the 36# one, be thankful and enjoy it, you are not going to hurt it. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />