Won't go to full cock in single action

[Murdock]

A long-delayed project is underway; I am converting an old Highway Patrolman to .44 Special using Jerry K's shop manual and George Nonte's old text Pistolsmithing.

With the new cylinder in the gun (an unissued one made during the run of 24-3's in the '80's), it cycles fine in DA, but just misses going to full cock in SA. You can feel it trying to catch on one or two chambers, but it won't quite hook.

Other than the cylinder, all other parts in the gun are original. It was in time when I started, so my reasoning is that the problem lies in the interface between the cylinder stop bolt and the bolt recesses in the new cylinder.

I'm thinking that the apex of the ball on the cylinder stop needs very careful and minimal polishing. Does this sound logical?

Thanks for any help.

 

[scooter123]

I would be inclined to suspect the hand is just a tiny bit too long for the extractor in your new cylinder. If so, it should be rather easy to determine if this is the issue, pull that hammer back as far as you can and test to see if there is some wiggle in the cylinder. If the cylinder is rock solid and won't move at all, you have the cylinder jammed hard against the cylinder stop and it's tying up the lockwork. BTW, just like the hammer, there is a tiny bit more movement on the hand in single action, which is why your timing is fine in double action but may be keeping you from fully cocking the gun in single action.

As for why this is so, it allows a much simpler lockwork. If you're using a revolver properly in double action the inertia of the cylinder will carry it into full lock, so there isn't any harm in letting the hand drop free a few thousanths "early". Even if you stage the trigger in double action and break it real slow, on a properly timed S&W the hand will drive the cylinder so that it's within the "window" of the forcing cone, so not much harm will result immediately, however over a long term that may tend to beat up the cylinder stop notches due to the bullet driving the cylinder into full lock. It's one reason why staging a double action trigger isn't the best way to use these guns.

Now, to correct for this, provided you've confirmed that the hand is truly a touch too long. Remove material from the driving face of the hand in very small increments, no more than 0.001 or .002 inch at a time. As soon as you can fully retract the hammer and feel just a tiny bit of wiggle, stop there and call it good. Personally, I don't like fooling with the timing on these guns, not enough hands on experience and fear of screwing up the gun. However it is a pretty simple geometry and working very carefully should get you where you need to be.

 

[Alk8944]

Murdock,

Will the gun cock in single action, or do it feel like the hammer is jitting something? Usually what happens, based on your limited description, is the strain screw is loose and the hammer strikes the end of the mainspring which lengthens as the arch is let out of it. Try tightening the strain screw.

It has nothing to do with the cylinder stop! If it was, the same situation would exist both single nd double action. Likewise it isn't the hand/ratchet fit as this would also be the same single and double action. The critical movement is the trigger, not the hammer. If it were the hand/ratchet you would feel stickiness at the end of trigger travel, and possibly the trigger would stick back.


Scooter, Please, buy a copy of Kuhnhausen and don't try to advise anyone on S&W Gunsmithing until you understand the mechanism, which you don't. The length of the hand has absolutely nothing to do with anything in a Smith. You are confusing Colt lockwork with this situation, and they are not even similar.

 

[bountyhunter]

Other than the cylinder, all other parts in the gun are original. It was in time when I started, so my reasoning is that the problem lies in the interface between the cylinder stop bolt and the bolt recesses in the new cylinder.

I don't think it can be that if it functions properly in DA because the same stop bolt is locking into the same cylinder notches in either DA or SA.

QUESTION: does it feel like the trigger is getting "tight" as you do a DA pull at the point where the bolt locks the cylinder? If you feel it getting tight, that is where the tip of the hand has to slip off the extractor ratchet and slide by the ratchet on the right hand side. A new cylinder may have enough metal on the ratchets to bind there (they have to be fitted).

If that is a new (unfitted) cylinder, I would assume that might be binding up a little there.

It is true that for the SA cocking motion, the hammer (and trigger) do come back a little farther than DA which corresponds to the hand being forced to go farther past that ratchet. If that fit is very tight, it might be binding it up short of full SA cocking position.

If the hand fit to the new cylinder is tight, DO NOT force it as that hand is very sharp and it will take metal off the ratchets. If this gun was mine I would pull the old hand off the trigger and put it in a bag with the original cylinder (which it is fitted to).

I would get a new standard width hand and fit it to the new cylinder. hands are cheap (about $12 at Midway) but extractors are a lot more pricey and harder to fit.

 

[Nightowl]

If after all this advice, you think the hand is too wide, take it out and measure the width across the top, and as suggested above, put it with your original cylinder and obtain new hands smaller than your existing one. Start at .002 smaller. Since its binding, I'm thinking you might even have to go .004 smaller.

 

[bountyhunter]

As far as I know, there are only two hand widths available which is the standard width and an oversized which is about .004" wider than standard. If my memory serves, the standard is about .094 - .095" and the wider is about .099" ballpark. I would buy a new one of whichever you now have (since you know it is a bit too wide but fits the frame window) and then stone the left edge of the tip as required to fit into the new cylinder's extractor. I believe Midway has spare hands for $12.