Revolver light primer strikes

[test drive]

was recently given a INA revolver by a elderly neighbor . Now before we get started I know the INAs are not well thought of but this was free and I need a project to work on while this Coronavirus stuff keeps me working from home. The gun is in .32 cal and looks to be in excellent condition . The problem is that it has very light primer strikes bad enough to not discharge but only on 2 chambers. The chambers are side by side. There is no or almost no play ( front to rear) in cylinder and lock up is very good. It has the old school fireing pin on the hammer. I have gotten it to fire those 2 chambers useing Champion ammo but it is still erratic. I’m thinking maybe the main spring ? But just on those 2 chambers is weird. Any ideas ? Thanks.

 

[herrwalther]

I had a similar problem on a S&W 64-5, misfires on 2 or 3 cylinders that were next to each other. Turns out someone bubba'd the mainspring to reduce the trigger pull. Which they did, but also made the firearm unreliable. I had the company armorer replace the mainspring, fixed the issue right away.

Take out the mainspring and see if one end has burrs or sharp angle at the end of the coils. This will show if the spring has been cut or grinded down.

 

[Col. Harrumph]

First thing, take it apart for a thorough cleaning and de-gunking, then a good gun oil. That may fix the problem, but if not and you're sure the firing pin is OK (swivels freely and isn't broken off short), you might replace the mainspring with gunpartscorp's SKU 1110120B.

 

[BBBBill]

Looks to be a near clone of a J frame Smith. If so it's probably subject to the same potential ills. Measure firing pin protrusion, cylinder end shake, and yoke end shake while you are playing with it. Correct as needed. J frames don't tolerate a lot of that being off, especially if the hammer spring is weak. I can set up a J frame for a light trigger pull with tuning and reduced power springs, but reliability demands constant attention to the above. Otherwise it will let you down just when you need it most. Far better to accept a heavier than you want trigger pull to assure reliability.
Also check carry up to verify that the cylinder is locking before the hammer falls.

 

[Slamfire]

Replace the mainspring before you get any deeper into this.

 

[edwardware]

Concur with others: measure FP protrusion, endshake, and headspace (rim-space here), and replace the mainspring.

If you really want to get into it, Kuhnhausen's S&W Manual is peerless. Your S&W clone should be similar enough to learn something.

 

[test drive]

Ok, I shimmed up the main spring with a small washer and though it is still not makeing the best of strikes the two chambers will fire. So I’ll order a new spring from Numrich. Thanks everyone.

 

[Kp321]

If it has a frame mounted firing pin, the FP spring could be either gunked up or too heavy. Recently repaired a Charter Arms that was doing the same thing. Had to clip half a coil off the FP spring.

 

[beag_nut]

If it has a frame mounted firing pin, the FP spring could be either gunked up or too heavy. Recently repaired a Charter Arms that was doing the same thing. Had to clip half a coil off the FP spring.

I also have a CA revolver, which has light strikes after 300 rounds. It ain't the firing pin spring; it's the mainspring (which weakens), which is why Wolff offers extra-power (heavier) main springs. I got one, and it has made the gun barely acceptable. Concluded that the gun is a piece of junk (as far as components are concerned). Clipping off the firing pin spring merely means that the problem will reappear in the future. Now am simply waiting for a local gun buy-back event to occur to get rid of it, with paperwork as proof.