Making a hammer spring?

[Gish]

Hey i'm trying to get some more power from my weak ass M870 gas shotgun. Trying to convert it to Co2 I've narrowed down a problem to the very weak hammer spring not being able to hit the release valve.
I was wondering if anyone knew how to make springs? I've heard piano wire but haven't found any information on that. Is there any other ideas someone could suggest?

[MadMax]

Hi Dave,

You'll reach a tradeoff point where a stiffer hammer spring can bash open the valve, but the return spring in the valve body can't overcome the hammer spring so the valve gets stuck open. You have to allow a decent margin between the preload force of the return and hammer springs to assure that the return spring in the valve body can overcome the stiction in the valve body (the friction in the valve body seals) plus the preload in the hammer spring.

Piano wire is available in most hobby stores that carry model trains or r/c aeroplanes. You can get a lot of wire diameters in 3' lengths from around 0.015" to 0.25". It's pretty hard stuff. You'll want a dremel tool with an abrasive disc to cut it. It'll mung your pliers.

When cranking the wound section experiment with a set of drill bits. Clamp a drill bit in a vise with the shank sticking upwards about 1". Use a couple blocks of wood so you don't chip the flutes if you have an unlined vise. Wrap the wire around the shank pulling tight on both ends of the wire. I like to use a pair of vise grips for this job. If you keep the tension high, the wire stays tight against the shank (in craftspeak this would be called a mandrel) and you get a constant diameter wrap. It helps to have a lot of extra length to grab onto so don't trim your wire before making a spring. Wear glasses as the wire can whip around pretty fast if you let go by accident.

Experiment with different mandrels to find which one gives you a coil which relaxes to the right diameter. Different wire gauges will require different mandrels to relax to the same coil diameter.