Light Strikes on a S&W Model 19-4

[Protocall_Design]

I don't like to say someone else is wrong, because oftentimes there are a lot of variables involved. I just say what I believe to be true, based on long term experience. There is plenty of room for other experiences and opinions. That's how you have a worthwhile discussion. Sometimes something will be absolutely wrong. Then I will say what I think or say nothing.

As for the springs, they have to be of good quality spring steel and correctly heat treated. I've seen plenty that aren't. The S&W (carbon steel) mainsprings have been consistently very good over the years except for the SS ones they made for a while. Those have an S stamped on them. They are junk.

 

[GypsmJim]

Did you clean the cylinders thoroughly so that the rounds are fully seated? If the cylinders have carbon rings, the hammer strikes will push the rounds forward until they are seated.

If the rounds are not fully seated, wouldn't the hammer strike be bigger?

 

[Marshal Kane]

No, some of the inertia in the hammer is lost pushing the cartridge foreward. The hardest "whack" your hammer nose is going to impact on the primer is when the cartridge rim is right up against the cylinder's charge hole.

 

[Beruisis]

Federal primers = good for light strikes.
Soft primer.

 

[Nightowl]

Personally, I do not use CCI primers! But, I want my guns to fire all ammunition reliably. In addition, I discovered years ago that a firm trigger actually aids in accuracy and a light trigger pull messes me up. You may not have the same problem.

Given the gun is in full spec otherwise, light strikes are virtually always mainspring issues. If it has a ribbed aftermarket spring, the strain screw will sometimes round and engage deeper in the open side of the V causing a lighter strike.

As Toolguy noted, Smith springs are excellent and seldom cause issues unless altered. I do not use aftermarket springs in any of my guns, except those few that come from the factory with ribbed springs, which I think they did not make. (Although I don't know that for a fact, but they look like Wolfe springs to me)

 

[Kurusu]

This may sound stupid but. Do you have another L or K frame around? If so try the other one main spring and see what happens. If it fires well get a new main spring.

 

[Kenneth07ex]

I would try the primer under the strain screw first. And if that works, I'd order a new mainspring. They're cheap, and easy to replace. Require no fitting, just remove, and replace. However, if you like that easy trigger, it'll probably be significantly harder with a factory spring. So I'd consider an aftermarket reduced power spring. Personally, I have trouble believing that's the problem, because you've said that it's only a part time problem. I'd think a weak spring would be always weak. But the spring is the easiest to check, so I'd certainly start there.

 

[ontargetagain]

Is there any chance you have changed the grips on this gun? The grip screw if in a different location could possibly interfere with the mainspring, and it doesn't take much as I once found out!
Did you by chance change the type of tool used to seat your primers?

Karl

 

[GypsmJim]

Here's an update...

No grip change and no change in the priming equipment.

I diligently cleaned the chambers with a brush and now I'm confident they are clean as a whistle.

Ran a box thru and all 50 fired first time. I DID notice a very slight difference in the depth and size of the primer strike, but none were as small as the no-fires before, and of course all rounds fired.

Thanks to all for the help and good suggestions. Were the chambers dirty, or is the spring still in question?