Won't Go Bang

[eliduc]

I'm trying out a S&W 586 that I can get for a good price. It seems to be in exceptional condition except that it misfires more than it doesn't when firing 38's. It seems to be ok with 357 mags but I only had a handful to shoot. To me it practically has a hair trigger in single action and a pretty light trigger pull in da. I'm thinking someone might have modified the mainspring screw. if there is much pressure at all on the trigger the hammer doesn't want to catch when fully cocking in single. I noticed the 357 cartridge bases seem to be just a hair thicker than my 38's. Could that be why they are firing and the 38's aren't? There is a dimple in the primers but it is pretty small.

 

[colt_saa]

Did you check to make sure the strain screw is tight?

 

[rog8732]

eliduc, I think your idea that the strain screw is loose or modified is the first thing to check.
After that, I have seen aftermarket grips, ( if you have those) bind on the hammer spring enough to cause light primer hits.

Since you mention S/A and D/A, trigger pull weight,I guess you found neither to be better than the other ?
Double action does not have quite as much hammer fall force, as single action.

 

[mark44spec]

If the strain screw has been shortened you can put a primer cup between it and the mainspring to see if that helps. It is likely that the mainspring and rebound spring have been replaced or modified. You can look at the mainspring and check for a rib in the center, that would indicate a replacement.

 

[stang1911]

Strain screw should be .480 long under head of screw sq. butt and .380 long rd. butt so the strain screw being tight means nothing if screw has been shortened.

 

[ontargetagain]

I see a similar problem when putting on a Wolff mainspring that it may not let the hammer go to full cock position in SA. What happens is the rebound spring slide moves forward and hits and interferes with the mainspring. The Wilson Combat mainspring has a different design that eliminates this problem as they put a different bend in their spring to clearance the travel of the rebound slide.

I have put a slight bend in the Wolff Springs in this area that allows for the full travel of the SA hammer and it will also lessen the DA pull by putting this arching bend in the mainspring.

The hair trigger can be from a very light return spring as well as mainspring or someone modified the factory angle on the trigger sear. This angle can add or subtract SA pull weight.

Karl

 

[papajohn428]

It could be an ammo problem, especially if you were shooting any reloads. Fired cases often have soot under the primer when reloaded, which can cushion the blow of the firing pin. If it's all factory ammo involved, a harder-than-normal primer might be the culprit, but I think you've been given good guidance about what to look for, mechanically.