Frustration at IDPA Match with 625PC

[Pizza Bob]

I wasn’t quite sure where it would be the most advantageous to post this, but decided on the Competition section in the hopes that there might be someone, who uses their revolver heavily, that may have experienced the same problem.

Let me preface this by saying that I have been down the whole light strikes, strain screw trigger job road previously, with another revolver – that one is all sorted out. The new problem occurred yesterday during an IDPA match. I was using a 625-8 PC. I bought this revolver, used, about six months ago. Really hard to tell how “fiddled-with” it was – it did have a Wolff mainspring in it, whether reduced-power or full-power I don’t know – feels like full-power (comparing it to aforementioned other gun, which has a RP spring). The strain screw was tight – but to be honest, I didn’t examine the end to see if someone had shortened it. Trigger is not all that light, but not bad and is decently smooth.

During the course of eight stages yesterday, I had multiple failures-to-fire (FTF) on every stage. The perplexing part of this is that when the failed rounds were examined, there was no evidence of a firing pin strike whatsoever. The rounds, in the same moonclip, that did ignite showed heavy primer strikes – to the point of actually causing some concavity of the primer cup Here is a photo of two moonclips each with two FTF’s

This gun has the firing pin in the frame. When dry-firing, and looking through the gap between the back of the cylinder and the recoil shield, you can see the firing pin fully protrude on each and every pull of the trigger. I should also note that up to this point, the round count, since I have owned the gun, is approximately 400 – 500 rounds, having shot several previous matches, plus re-sighting the gun after changing out the front & rear sights. Never a bobble – ran 100%.

The only thing that I can think of is some kind of firing pin malfunction – either debris in the firing pin channel that randomly blocks the FP’s forward movement, or some kind of fracture resulting in the same symptom. Hammer strike on the FTF’s sounded the same, but that is a very subjective judgment. I have not yet disassembled the gun to actually examine the firing pin. I figured I would go ahead and order an Apex Competition FP (.495”) & spring, to reinstall before I disassemble it. Never having removed a S&W in-frame firing pin before, it appears that there is a retention plate, on the hammer side of the FP, that fits in a channel that can be accessed with the sideplate removed, much like a 1911 firing pin set-up (albeit with a much shorter pin), correct?

I’m really stumped and hoping that this isn’t a unique problem and someone can point me in the right direction. Thanks for any help offered.

Adios,

Pizza Bob

 

[Jim Watson]

You mean it "snapped" on the two rounds in each clip that do not show a mark at all?

I don't think a longer firing pin is going to help, the ones that were hit were hit hard.

I see two possibilities:

The firing pin SPRING is broken or squashed. My Python did that once. The frame firing pin could get bounced forward to where its head was not protruding back to be struck by the hammer.
Easily checked, just prod the head of the firing pin with a punch and see if it is spring loaded to the rear.

The hand is out of whack and the cylinder is not indexing every time.
Shoot the gun at a match rate of fire and STOP when it fails to go off. Then look to see what round is under the hammer.

 

[MKT]

There is another possibility - short stroking the trigger. On the older guns that would have been close to impossible as everything would lock up but with the newer guns it can happen, The trigger will move a very slight amount and the cylinder will rotate and you think you have a light hit. The fact your primers have no marks on them leads me to think this is what is happening here.

You can double check the rebound spring to ensure it hasn't been cut a hair too short, IIRC 13 or 14 coils is the minimum and I would think 15 or 16 should be fine. If too short the trigger may not be fully resetting.

 

[Pizza Bob]

The hand is out of whack and the cylinder is not indexing every time. Shoot the gun at a match rate of fire and STOP when it fails to go off. Then look to see what round is under the hammer.

Thanks to MKT also, but I think we have a winner here in Jim's second possibility. I was able to duplicate this while dry firing. The cylinder is not indexing fully, when the trigger is pulled rapidly. It just kind of floats and is not locked when the hammer falls, so the FP hits between chambers.

OK, Jim, the $64K question - actually two - 1) Why would it start doing this all of a sudden - coincidental with the first stage of a match (it was cleaned and lubed prior to the match, but the sideplate was not off - would a drop of CLP down the slot where the hand moves to engage the rachet do this somehow?); and, 2) How do I fix it? New hand? Send it back to Smith? Local gunsmith?

Thanks.

Adios,

Pizza Bob

 

[scooter123]

IMO the cause could be one of three possibilities.

One is a broken firing pin return spring. Cylinder & Slide quite specifically warns that Snap Caps absolutely MUST be used with their firing pin for ALL dry firing. As for why, the C&S firing pin features an extended travel slot in addition to an extended length and they can "wad up" the return spring if a Snap Cap isn't in place to "catch" the firing pin.

The second is short stroking the trigger in double action. Normally you would immediately notice the much lighter trigger pull of a short stroke but in the heat of competition that might go unoticed.

Third possibility is a short strain screw. The stainless steel strain screws do "wear" shorter at a surprizing rate. The actual process is peening instead of wear but the result is the same, you suddenly can see misfires start to occur. BTW, this is much much more likely in a revolver that has been "tuned" to the borderline because just a 0.005 inch change in length can mean the difference between reliable ignition and misfires. Personally I would recomend you replace the stainless strain screw in your 625 with one in blued steel because they seem to be much harder.

 

[OKFC05]

The cylinder is not indexing fully, when the trigger is pulled rapidly.

I was waiting to see if this was the case. I bought a used 66 that was also skipping in rapid fire.
It took $168 worth of parts for a very good revolver smith to make it 100%. Not to discourage, but I doubt there is any quick fix; it needs to come all the way apart in the hands of an expert.

 

[H Richard]

A possible cause of the short stroking is a "too light" of return spring installed to "lighten up" the trigger. I never use lighter than a 14 llb. and normally a 15 lb.

 

[jackpearl]

Might be a weak or disconnected hand spring.You could pull the side plate to check very easily for tension.

 

[imashooter2]

A possible cause of the short stroking is a "too light" of return spring installed to "lighten up" the trigger. I never use lighter than a 14 llb. and normally a 15 lb.

I had a 12 in one of my revolvers and had to go up to a 14 for just this reason. On the close targets, I was trying to shoot faster than the trigger would reset.

 

[snubbyfan]

The last time I saw a revolver with this problem it turned out to be a weak cylinder lock spring. It's hard to tell without having the gun here to examine and diagnose.
Remove the sideplate, disassemble it, clean and relube. Sometimes that all it needs. It might just be gunked up.