S&W Model 66-2 Firing Pin Problem

[16in50calNavalRifle]

Well, at least it's a problem related to the firing pin.

Model 66-2 4", third owner, saw very little use by previous two, has worked perfectly for me for 3 years.

At a match the other day, right out of the gate, several failures to fire. Ammo was my own reloads (never a FTF with this ammo in the past) - 125g RNFP over TrailBoss with CCI 500 primers.

FTF cases showed firing pin strikes off-center - and shallow - on the primer, one strike in the gap between primer and case, and even one completely on the brass, just next to the primer/case gap (pocket). The three that fired properly showed the typical deep, centered crater in the primer.

Inspection of the revolver reveals nothing (to my eyes): lock-up and timing and end-shake all fine, firing pin SEEMS normal (i.e. its pin looks OK and it moves a bit, as I think it should).

Have a hunch this is not the first time this has happened in the world. Anyone ever seen this particular problem with a K-frame, and what was the solution?

 

[David E]

Sounds like the hand is broken or worn.

 

[Kp321]

+1 on worn hand or cylinder ratchet star. Off center strikes indicate a timing problem, strikes on the brass mean a serious timing problem. An off center strike that fires would spit lead like crazy! Don't shoot it till the problem is resolved.
After more thought, need some information. Is the off center strike early or late? If early, worn hand could be the problem. If late, this indicates the cylinder lock bolt (or what ever Smith calls it) is not stopping the cylinder rotation. Could be a burr on the bolt, a weak spring or crud in the channel it sits in.

 

[BBBBill]

^^^^^^ As noted, it ain't the firing pin! Could be poor carry up (hand issue) or throw by (cylinder stop issue). Look for a broken/worn hand, weak/broken hand spring, worn ratchet, worn/broken cylinder stop, weak/broken cylinder stop spring, crud binding the stop in the stop window, worn stop notches in the cylinder. Also any evidence of any previous inexpert gunsmithing that may be just now raising its head.

 

[16in50calNavalRifle]

Thanks for the feedback, guys. While I don't hesitate to tear a Mosin (or maybe Garand) or 1911 apart to tinker, revolvers are unknown mechanical territory for me, so I've contacted S&W to seek their advice (they're on their summer shut-down this week). Your comments make me think is something more complicated than a firing pin or related spring.

 

[4v50 Gary]

Bad primers?

Did you loosen the mainspring screw on the grip? Some folks do it mistakenly thinking they're adjusting the DA trigger pull.

 

[16in50calNavalRifle]

Gary, no, I've not touched the revolver other than to clean it. Primers are fine - the ones struck normally and hard in the middle all fired, and there have been no malfunctions before in the time I've owned it. And the ammo was from the same lot I've been firing from this revolver at the same matches every month for a while now.

The primer strikes all over the place seem to be the key here. The pin is not hitting where it should every time, or with the force it should. Not sure what's going on, but firing pin marks off the primer and on the brass indicate a gun problem to me, not an ammo issue.

 

[dfariswheel]

In a revolver, firing pin strikes off the primer are a sure and certain symptom of a timing problem.

If for whatever reason the timing is off or there's a problem with the cylinder locking bolt or cylinder locking notches, the cylinder will either not rotate far enough, or it will have "throw-by" which is the cylinder rotating TOO far.

In either case, this is SERIOUS and the gun is unsafe to fire.
Since in either case, the cylinder chamber is not aligned with the bore at ignition, you have the gun firing in an un-locked condition and bullets hitting the side of the barrel.
This means the gun will spit bullet metal dangerously and can easily cause serious harm to the shooter or a by stander.
This can also cause serious damage to the gun.

Stop shooting the gun until you can get it repaired.

 

[rcmodel]

+1, 1,000%!!

There is no way a revolver can hit that far off center if it is locking into battery as it should before the hammer drops.

It has nothing to do with the firing pin.

It has all to do with a cylinder timing problem, as outlined by dfariswheel in the above post.

Stop shooting it until you get it fixed.

I would suggest a trip back to the mother-ship at S&W if you are not a revolver-smith.

rc

 

[16in50calNavalRifle]

dfariswheel and rc, fear not, I stopped shooting it immediately when I discovered the problem. I have contacted S&W - they're on a summer break - describing the symptoms. Expect they will get back to me next week.

I am no revolver-smith, so I won't be touching the thing other than to get to someone who knows that to do.

Thanks for everyone's input here.