I am looking for a mainspring for a S&W Model 43 Airweight .22LR

[Harry O]

I am having occasional failures to fire with light firing pin strikes. The gun is old, from the late 1950's or so. My first plan was to replace the coil mainspring.

I understand that .22LR J-frames have heavier mainsprings than the centerfire models (12# or 13# depending on the source). Wolff Springs doesn't have them. They have light 9# springs (or even lighter) mainly for centerfire models. Numrich Gun Parts, Brownells, Smith & Wesson, and Midway don't have a replacement for the Model 43. A general Google search failed to turn up an actual factory replacement spring. I did find a current S&W .22LR Airweight spring, but it is for the Model 317 and I don't know if that will fit.

Any suggestions? I am thinking of putting a couple of small washers on either end of the spring if I cannot find a spring, but I would rather have a real replacement if possible.

[Outpost75]

The 9mm mainspring for the J-frame model 942 is 13#

[rintinglen]

Put a washer in place. Try it. If it works well, hooray, if not, call S&W direct and order direct. If they don't have a Model 43 spring, a model 317 spring should work as well.

[Drm50]

43 Spring is same as 34, J frames. The K frames had leaf type spring. 43 is scarce model. Dont
Bubba it, buy a new main. Someday you will be glad you did. All Js from same period used same
spring, you don't need a heavier spring just a new one. S&W has them.

[DougGuy]

How easily is your ammo chambering? I just had a Model 34 cylinder come through the shop for cylinder work as the chambers were so tight lots of factory ammo didn't want to chamber, and half the stuff that did, got light firing pin strikes because it wasn't seating fully in the cylinder. It also suffered from stiff extraction with different brands. Just a thought as the issue may not be 100% caused by the spring. The throats were fine, but the chambers themselves were the problem and it was fixed by using a Manson reamer in each chamber then polishing. The gun gobbles up all brands of ammo, gone are the stiff extraction problems, and gone are the light firing pin strikes.

I am also under the impression that modern ammo is not made to the tolerances it was decades ago, because the Model 34 didn't have those problems until recently. This could also compound the light firing pin strikes issue.

[Harry O]

Thanks for the suggestions. I can get a Model 34 spring. I wondered if it would fit, but it is worth a try. They are from the same era and it makes sense that they would be interchangeable. The ammo is chambering easily and seats solidly. I don't think that is the problem. I also wondered about the firing pin. I have had the gun for about 10-12 years, but it could have been dry fired a lot before that. If the spring doesn't work, that is my next guess. The firing pin doesn't look "different", but I am no expert.

My wife took over the gun from me several years ago. When she started having problems, I verified it myself. She likes a "cute", little, lightweight gun that is accurate and has little recoil. So I have to get it fixed.

[rintinglen]

A thorough cleaning may also be in order.

I have a 1973 K-22 that demands that I keep the cylinders clean or else I have difficulty getting the cylinder to rotate because the cartridges don't fully seat. You may be running into a problem with dirt or old lube cushioning the hammer blow. Take off the grips and soak the gun in mineral oil in a covered container, maybe agitate it a Little to remove some of the crud and see if that helps. I would also encourage you to try a washer on the hammer strut. If the problem goes away with the washer, then you are probably correct in defining your problem as being the spring. If it does't go away, you will need to look elsewhere.

[Harry O]

A thorough cleaning may also be in order.


A thorough cleaning was the first thing I tried, including taking the sideplate off and cleaning inside. No change.