Cutting hammer springs

[Eargesplitten]

I'm working on a TZ-99, which is like a Zastava CZ-99, and want to replace the hammer spring because it's excessively heavy and I suspect part of that is to brute force past the terribly rough finish quality on all of the parts, which I've remedied with liberal use of sandpaper and polishing compound. The problem is there's only one option, it's scarce in the states and the first result searching for it is someone finding a workaround for light strikes it caused. I was looking for alternatives meant for other guns, but the problem there is that the hammer spring is 48.25mm long, seems to be an uncommon length. ID and OD is the same as my SP01, but it's about 14mm shorter (measured with calipers). I saw that David at CGW actually recommends just cutting full-sized hammer springs to fit the subcompact RAMI, I was wondering what sort of finishing should be done after cutting a spring, since it would be missing the flat coiled base at the bottom or top. I could heat it up and bend it into shape, but I would be worried about ruining the existing heat treating.

 

I was also wanting to make sure that I understand how hammer springs are measured. The pound rating is what it takes to compress the spring an inch, correct? The equivalent to k in hooke's law? So if I was cutting off about 20% of the spring to match lengths, I would add 25% to find the new rating of the spring? Since cutting a spring in half doubles it's k value, cutting 20% off (leaving 8/10ths) would result in it having 10/8ths the k value, or 1.25 the original. Or is the pound rating measured in some way unrelated to the k value?

 

Thanks for the help, I realize this is a somewhat unusual question. Not a lot of people working on $250 South African knockoffs of late cold war Yugoslavian designs.

[Eargesplitten]

Follow-up question since I realized there are dozens of places that sell music wire springs and all you have to know is the dimensions and the weight you want. Gun springs are generally measured in load, right? Not spring rate? When a shop sells an X pound spring, that's what it takes to compress it completely? I found a couple with loads between 16.7 and 18.7 pounds that would fit, just need to figure out how much shorter this spring should be to get rid of the stacking.

[MemphisMechanic]

If you take a pair of calipers to the factory one and figure out it’s dimensions... you’ll likely find that a hammer spring from a CZ or some other application will work, if you dig.

[MikeBurgess]

Looks a lot like a Sig may see if Sig springs fit.