Walther LPM-1 Hammer spring

[tkinva]

I recently acquired a Walther LPM-1 pistol. At first, its performance was very erratic, with the FPS all over the place. I finally figured that the hammer spring didn't have enough tension. I was just about to start disassembling the pistol when I noticed a hole in the back of the grip and the screw to tighten the hammer spring. So I tightened it and the pistol started behaving normally.

But now I need some guidance in tightening the spring. How much should I tighten it?

[Rover]

If you're happy with how it's shooting, you're good to go. If you have a chronograph, you will probably be able to get around 490 fps max with a 7gr pellet.

I think I recall putting in a spare spring from another brand of gun. No big deal.

BTW I consider mine to be a real "keeper"....super sturdy.

[tkinva]

If you're happy with how it's shooting, you're good to go. If you have a chronograph, you will probably be able to get around 490 fps max with a 7gr pellet.

I think I recall putting in a spare spring from another brand of gun. No big deal.

BTW I consider mine to be a real "keeper"....super sturdy.

Thanks for the advice.

This is a beautiful pistol. I already had a CPM-1 and it took me over a year to find the LPM-1. This pistol is a lot of fun to shoot.

First I tightened the spring until the hammer held the valve open at the end of the shot. If the valve remains closed, it becomes hard to open the pumping lever. Then a couple of turns after that. I finally turned it carefully until it stopped.

Many years ago, there was an engineering instrument that used a vibrating wire as part of the assembly. The instructions for tightening the wire read, "Tighten the wire until it breaks, then back off half a turn."