3" Model 60 Misfires

[conagher]

I have a fixed sight, 3 inch model 60. I bought it used but it appeared to be in excellent condition. I shot a couple of boxes of new ammo through it and it shot reliably. I had the hammer bobbed and it started misfiring. The hammer would hit the primer but it would not go off. It mostly happened with reloads, but sometimes with new, factory ammo. My friend that owns the local gun store changed the hammer spring(I guess that is what it would be called) three different times but it still misfires. The last spring he installed makes it extremely difficult to pull the trigger but it will still misfire some. The only other thing he thinks could be causing it is a short hammer. I know nothing about how a revolver works so any suggestions would be appreciated.

 

[nvgunner]

What kind of ammo did you use? This happened to me using Sellier and Bellot .38 ammo--during my CCW requalifying test. I was using a
S&W model 64 and multiple rounds failed to fire, despite the hammer striking the primer. I got some different ammo, the gun worked fine,
and I have not bought that brand since, have had no similar problem w/ other new brands or reloads. I did nothing to change my gun.
Just my own experience--your comments caught my attention.

 

[500 Magnum Nut]

You need to check your end shake, it must be less than .002 inch. Clean under your extractor and make sure it is dry. Check your firing pin that it's not chipped.

Make sure that you are using a "factory" full power main spring.

 

[conagher]

NV gunner- Most of the misfires were with old reloads. However, my other .38 specials shoot the same ammo fine. At least one of the misfires was with a factory load. I think it was either Federal or Remington. I know it was not Sellier & Bellot.

500 Magnum Nut- Under the extractor looks O.K. The firing pin looks O.K. What is end shake?

Thanks for your advice.

 

[500 Magnum Nut]

Grab the cylinder with your fingers as the cylinder is closed. Then push it forward then pull it rearwards. The slight motion is end shake. It is measured precisely with feeler gauges placed between the forcing cone and cylinder face.

See the sticky above for further steps is checking it.



What may be happening is if there is too much cylinder play, the firing pin is pushing on the cylinder while trying to pop the cap. The end play is acting like a shock absorber cushioning the firing pin blow.