Pre 18 Light DA strikes…

[45Smashemflat]

Just to clarify current state. New mainspring. New (unmodified) strain screw. (Measured 55oz hammer weight.). Added shim from 22 case scrap. (Have not measured hammer weight yet.)

 

[steelslaver]

A new rim fire main spring and screw are not the same as a new center fire main spring and screw. My suggestion of getting a new screw from Ace is so you have an over length screw to start with.

Just because one K22 works with a 55oz hammer weight does not mean yours will. To many other variables. They do not all have exactly the same headspace, endshake, firing pin length, firing pin spring etc. Don't get stuck on the numbers. Find what works

IF you start from 100% reliable and adjust to failure to fires you KNOW where your at. I have 4 K22s and everyone of them fires every time.

BTW Your firing pin should stick out about the thickness of a dime. Open cylinder, Hold thumb piece back, pull trigger and hold it back, slide dime beside firing pin tip

 

[Protocall_Design]

You will more likely need around 70 oz. + or - hammer weight to reliably fire rimfire ammo.

Edit to add - The mainspring on all K, L, and N frames is the same one. The original tapered S&W mainsprings are super high quality, and the ones I like the best. Also, because they are correctly tempered, you can bend or straighten them and they stay will hold that shape. The exception is the stainless steel ones that have an S stamped on them. Those do not work well.

 

[45Smashemflat]

Is there a difference in the Rimfire mainspring? I'll certainly Google up Ace and see what they have.

70 Oz, wow! Ok, I'll have that as a target.

 

[steelslaver]

All Ace stores have gun screw and I don't find them searching their web sites. The gun screws are found as one of the sets of the small boxes of various screws, fastener etc.

I have also found the same gun screw kits in the Big R farm and Ranch stores in this area of the country.

But you can use any 8-32 screw, but hardened ones are best. Some guys use ones with Allen socket heads, but the gun screw selection has ones with the same head as the factory. Plus, stuff like various scope mount screws etc from about 0-80 up to 8-32.

The kits also have a small metal plate with lots of marked screw sizes drilled and tapped in them. Not only are they handy for figuring out what size screw you have, they also work well to thread a screw in tight and hold it so you can grind or file it to the length you want

 

[45Smashemflat]

Ok, measured the hammer weight with the small shim, it's 59-60oz. This is with a Wolff extended strain screw and a snip from a 22LR case. I'm going to head to my local Ace to get a screw I can experiment with. Unfortunately, my Ace does not carry the gun screw selection. I'll do some testing with whatever I can find, then order something I can make work that will look better.

 

[steelslaver]

PM me your address and I will send you 2 slightly over length 8-32 screws with the correct head. Both Ace and Big R have them here.

 

[Protocall_Design]

I just use an 8-32 socket set screw. Set screws have no head, so you aren't limited in adjustment. For square butt, 1/2" long, for round butt, 3/8" long.

With a setscrew, you have to use blue 242 or purple 222 LocTite to keep them from moving outward as the spring is cycled.