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Discussion Starter · #1 ·
Took my step-son shooting yesterday and since he and I mostly shoot semi-autos these days I thought it would be nice to go old school and take a revolver along. I had inherited a S&W M66 from my dad and since I had never shot it, I opted to take it along. When we started shooting it, I noticed that at least once in every 6 rounds, a round would fail to ignite. The round would fire after re-seating it. I've always thought the trigger was super smooth and light so always figured it had been worked on.

Question: Is this a good sign the trigger has been lightened up too much, or is there something else I should look at first?

Other than that, it was nice to appreciate what a good revolver is like to shoot.
 

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Hello. Yes, that's a sign of what you mention as a possible problem. It's also possible that the strain screw has been backed out or worked look. It is toward the bottom of the front grip strap and may be covered with the grips, depending upon what style they are. This screw should be in all the way.

Best.
 

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Discussion Starter · #3 ·
Stephen, thanks for the quick reply. The strain screw had backed out about 3/4 of a turn. Think that would be enough to effect it? I hope so, the trigger pull on it is sweet and I don't want to mess with it if I don't need to. Hopefully can get back out next weekend and put some more rounds thru it and see if the problem is fixed.
 

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Are you shooting reloads.?? Sometimes a primer will not ignite the first time if not seated all the way to the bottom of the pocket. Someone might have also played with the hammer spring, or put in a lighter one. If problem persists after cleaning out the chambers well, and trying factory loads, try a new wolfe spring.
 

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FWIW:

1) Yes, 3/4 turn out will definitely make you prone to light strikes.

2) A light DA pull probably means either a reduced power spring was installed, the stock spring was machined along the edge, or the end of the strain screw was ground off a bit.

Any of the above make a gun likely to have misfires on a stiff primer.

I tune and shoot SW's in comp a lot and set them up light. Every now and then you run into a stiff primer nd hear the "click". Good way to see if you're flinching, which I usually am. Best to stick with the very soft (Remington) type primers with light spring guns. I got a batch of new UMC ammo and had a bunch of misfires using it.

You can increase the hammer force back up to stock by installing a stock mainspring and strain screw (very easy to do).
 

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My 629 Classic will start to missfire if the strain screw backs out even starting at a 1/2 turn.

I make a habit of pulling the grips and checking it every time I clean it even though I blue loctited it. It keeps the oil and bore cleaner from the wood as well so it's a good practice (for me).

Dog
 

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Discussion Starter · #8 ·
I hope that's all it is, like I said, the trigger is sweet the way it is. My other fear was that the ammo was too old, and I was getting some slow burns. On every 'click' I was holding 10 to 15 seconds just to make sure. The ammo was issued to me back in the late-late 80's and early 90's. If that's the problem, then my whole stockpile is bad, 700+ rounds.
 

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IMHO, if the strain screw being out 3/4 turn causes misfires, that gun has been set entirely too light. There is just no margin for any discrepancies, like hard primers. Some will say that misfires are an acceptable tradeoff for a light pull on a pure range gun; I disagree. On a range gun they are a figurative pain; on a defense gun, they can mean a literal pain or maybe the end of all pain.

Jim
 

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Jim Keenan said:
Some will say that misfires are an acceptable tradeoff for a light pull on a pure range gun; I disagree. On a range gun they are a figurative pain; on a defense gun, they can mean a literal pain or maybe the end of all pain.

Jim
Depends. I have a 686 that I lightened to a DA pull of 5.2# by reducing spring force and doing a major amount of polishing. It was strictly for a comp gun and never misfired with the reload ammo I used in it which had soft primers. I have had an occasional misfire with some crummy new ammo (UMC), so I set the gun up with a shim on the strain screw so I can adjust the mainspring force if I need to. Optimum set point is about 1/2 turn out from bottom (use blue loctite if you do this), which gives me some headroom to crank up the mainspring force if I run into stubborn ammo.

I don't think anybody suggested reducing the mainspring force in a defense gun was good idea. My model 10 for defense has stock springs.
 
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