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JAG1949

S&W revolver troubles

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I recently acquired a S&W 625 .45acp revolver.  I'm sure it was owned by a competitive shooter because the trigger has a stop installed on the rear surface and there is a ball detent in the top of the crane which securely locks the cylinder in place.  The problem is when the trigger is pulled quickly for rapid fire the cylinder often jumps two chambers rather than just one.  It cycles normally in slow fire and single action.  Upon initial examination I determined the hammer block had been removed.  I understand this is a common but by no means safe procedure to speed up the action of the revolver.  I replaced the hammer block but it made no difference to the skipping problem when in rapid fire.  All this testing has been done with a empty pistol.  I'm not about to risk life and limb with a mistimed revolver.  Returning it to S&W is an option but I'm comfortable replacing parts on the gun if I know where to start.

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It's been some time since I was inside a revolver, but it seems to me that it would have to do with the cylinder lock.  It is not rising to engage the notch in the cylinder in time.  That may be a spring problem, or that the lock itself was modified (perhaps shortened) such that it rises late in fast cylinder rotation.

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Most likely there are burrs on the stop notches on the cylinder. take a look at the side of the notch that is relived, right at the end of the relief where the notch is it is likely you will find a small raised edge where the metal has been peened up and can cause the cylinder stop to jump the notch. you can carefully remove this lip back to a square corner (not round) and it will likely improve the problem. also look at the cylinder stop make sure it is moving freely and not gummed up and moving slowly for any reason, also ensure its smooth and square.

 

The hammer block is really only there as a drop safety, as in dropped with the hammer cocked, so it a common modification on competition guns because they are almost never manually cocked. (mine are never manually cocked)

Edited by MikeBurgess
spelling

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If you give us your general location, maybe someone local can help you in person. In the meantime, here are a few things to check out.

The main reason to remove the hammer block is to make the trigger return easier with a light rebound spring. That is a bad idea, as you correctly surmised. The way to make it work with the hammer block in is to smooth up the long sides of the triangle hole in the bottom so the pin on the side of the rebound slide can move in the hole smoothly. Also, flat file the sides and make sure it slides freely in the slot of the sideplate. File a generous chamfer on the front and back sides of the top of the flag so it can return upward without catching on the frame or the hammer.

 

When a revolver is used a lot, especially at higher RPM, the inertia of the cylinder turning, then coming to a sudden stop, creates burrs on both sides of the cylinder stop notches. It's likely that the burr on the ramp side is causing the stop to bounce down out of the notch when rotated quickly. The fix for this is to peen the metal on the cylinder back where it came from. On the ramp you can use a 5/16" round steel bar on it's side (the size and shape of the ramp) and tap the bar with a hammer to iron it out. On the other side of the notch, you can use a flat ended punch (maybe the same 5/16" bar) using the end of the punch to move the material back where it came from. If this does not fix the problem, let us know, with more information and we will try something else.

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I've checked the cylinder lock notches for burrs and deformed metal and I have been unable to perceive any.  The cylinder lock itself is shiny on one side but does appear to have worn away any metal.  I was advised to check the cylinder lock spring and while it is in place and returns the lock when depressed I have no way to determine whether the spring is correct or has the required tension.  I'm in SE Texas between Huntsville and Livingston on the north end of Lake Livingston.

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I always figured they gave up some spring load on the cylinder stop when they dropped the 4th screw and required the stop spring to be crammed in place from the side.

Wolff makes regular and extra strength stop springs.

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On 6/10/2018 at 11:26 PM, JAG1949 said:

I recently acquired a S&W 625 .45acp revolver.  I'm sure it was owned by a competitive shooter because the trigger has a stop installed on the rear surface and there is a ball detent in the top of the crane which securely locks the cylinder in place.  The problem is when the trigger is pulled quickly for rapid fire the cylinder often jumps two chambers rather than just one.  It cycles normally in slow fire and single action.  Upon initial examination I determined the hammer block had been removed.  I understand this is a common but by no means safe procedure to speed up the action of the revolver.  I replaced the hammer block but it made no difference to the skipping problem when in rapid fire.  All this testing has been done with a empty pistol.  I'm not about to risk life and limb with a mistimed revolver.  Returning it to S&W is an option but I'm comfortable replacing parts on the gun if I know where to start.

JAG1949,

 

The respondents to your post gave excellent advice. Yes look at the cylinder lock, spring, re peen and lightly remove any burrs on the cylinder. Did someone do a "trigger job?" You may want to look at the strain screw. (Remove the grip) it is the slotted screw that tensions the "leaf spring" located toward the bottom of the grip. Some loosen this screw to get a lighter trigger pull. It will lighten the trigger pull but can cause timing issues due to spring tension imbalance. The strain screw should be firmly tightened. IF the trigger pull is "too heavy" then perhaps an after market spring kit is needed.

 

If this does not work. Here is my story. I own a 1989 stainless 625 5 in bbl. I would not send your firearm back to S&W, I have a post here where I explained the concern. In the end S&W said it was something I was doing... Yeah ok. 

Bottom line what finally fixed my revolver was. I had the stainless steel cylinder replaced with a titanium one. 

 

Randy Lee @ APEX Tactical  He is in Los Osos CA

(I am not Randy Lee)

 

That 625 is a fine firearm. 

BTW - Since replacing that cylinder I have been dryfiring my 625 3-5X a week, the 6 reload 6 drill, strong hand, weak hand, both hands, 10X each as fast as I can. I don't get to the range much but. Still has not skipped. I use dummy rounds, non primed wolf steel case with a copper jacketed 230gr rn bullet. I have been doing this since 2013...

 

Best wishes with your 625,

Randy Pizarro

USPSA TY27966

ICORE CA8491

NRA Life Member CVD 5294D

 

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+1 for replacing the cylinder stop spring and checking to see how worn the cylinder is itself. I bought a well used model 10 with this issue and changing the spring worked in that particular instance. 

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All the advice here is good. The cylinder stop or stop notches in cylinder would be the culprit (whether worn severely, weak spring, or compromised interaction between the trigger preventing reset) to allow any rotation beyond the next chamber in rotation. But what puzzles me is how (according to how I understand your description) it is skipping a chamber, landing two chambers away and locking up with the stop. Momentum from running hard double action is still quite a stretch to move a loaded 45 ACP N frame cylinder that far in a six shot as its quite the rotational distance to cover.  (I can see it possible in 8's and definitely in 10's with much less rotation between chambers). I would see it more probable to land just past the next chamber but prior to the stop notch 2 chambers away. Im not saying its impossible, but seems likely  if its happening and locking up two cylinders away consistently it indicates to me on top of a cylinder stop problem you have a hand/ratchet problem. The hand is staying engaged on the ratchet too long and continuing to push the rotation beyond where it should be timed to release. If so that will most definitely contribute to stresses applied to that stop or the notches and caused this problem in the first place. Before this started did you happen to notice if the trigger loaded up towards the end of the double action stroke, like almost hitting a wall before continuing rearward or felt increased resistance when cocking to single action just after the cylinder stop engaged a notch? If so you got a mistimed hand problem too! Im mentioning this just in case you have a compounded problem and before you start throwing parts at this thing just to find out its still not right etc. It may not be a bad idea  to look up a Revolversmith to diagnose and repair. 

Edited by BallisticianX

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