IZH-35m recoil spring

Does anyone know of an alternative recoil spring for an IZH-35m? Thanks in advance for your help.

I made a copy of the IZH, Adam shot it at Perry, won .22 Junior 2 years is a row with it. I can measure the spring used. Grips are not what Adam used they too were home made. Adam altered them to fit, Plastic wood and Body filler used when changes made. Larry Guns had IZH Rink grips on sale very cheap so got them and fitted to my IZH after Adam joined the Army AMU (little plastic wood was needed, I didn't include the grip safety) Also opened up the breech. Cover plate was off on the other side that covers the hammer spring, it wrapped around and covered the hammer slot. Not often but once in a while empty brass would get into the slot if it wasn't covered. Otherwise gun function great with the spring used with standard velocity CCI  ammo. Being there is no slide stop I used the heaviest spring that would allow the gun to function, you might try that. You can check spring companies, select springs with different wire diameter. Since shot fired is with the bolt closed I want as much spring pressure on the closed bolt as possible on ALL my guns! But limited to gun function so ammo selection is needed so use ammo spring was selected with.

Call Wolfe they might know, I Bet a FAS or and AW spring would work but that is just a guess

It's remotely possible that a Ruger MK spring would work.  You can buy those from Wolfe.

If I recall correctly when I talked to Wolff they could not provide dimensions. They have springs that were designed to fit guns listed but not have dimensions for them. MCMaster Carr has online catalog with stock compression springs but their choices are kinda limited. Might be good to search spring companies that have in stock springs.

Here is a good company that makes springs by the bushel.  They have a prototype department… 

https://www.asbg.com/products/custom-component-prototypes-short-runs/

Years ago, Brownells sold a pack of miscellaneous springs but they may have dropped them

If my memory is correct Brownells has 3 spring kits, maybe only 2. I know I have  all the spring kits Brownells sells but selection is kinda limited. Again if my memory is correct I didn't get a spring I could us as a .22 recoil spring, none were large enough to be used as 1911 recoil spring. I may have used a 41 recoil spring from Wolff in my homemade version. They have selection from 6lb to 8lb in 1/2lb increments.
 Problem with Associated Spring (link provided by Wobbley) is they are a custom spring house, one spring will probably cost a fortune. If you were a large corp. they would probably make a few samples at no charge.
 Need to find a company that sells stock springs. I know there was one in PA but can't remember name. I try searching for them.

Thanks for all the suggestions, everyone. I tried Wollf and they are of no help...

Why do you want to change the recoil spring?