Just sharing some info that I hope some folks will find useful.
This site is obviously dedicated to NRA Highpower Rifle. However, there is just a wealth of articles on many topics, including springs. All of them are in PDF format and free to download.
I have a Ruger Mk I standard 22 pistol that I bought new in 1974. Today it is pretty much "Kentucky Fried"--parts is parts--to include a SS AMT heavy barrel top end. I managed to snag the AMT before Ruger took offense and legal action--"I say lads, I believe that's our patent you're infringing on".
Recently I had begun to notice a sharpness in the recoil, metal contacting metal. Obviously, the bolt was starting to slam into the bolt stop pin. So I got on of these kits--
I simply installed it as it came with the standard weight spring. I went to the range and tested it out with this ammo--
Flawless function, no more metal on metal. My main point is that this kit DOES in fact work for the MK I, even though Volquartsen does not list it.