Hammer Nose binding cylinder

[commygun]

I’m going to describe what I think is happening and would be grateful for any input. I may be barking up the wrong tree entirely.

When shooting my S&W 1917 revolver, a couple times per cylinder-full the gun will bind up. I can’t thumb back the hammer or move the cylinder with the trigger. If I wiggle the cylinder gently, the hammer is freed and the gun functions normally until the next time this occurs. This only happens with live ammo and it doesn’t make a difference if the cartridges are loaded singly or with a moon clip. With the cylinder empty or loaded with fired cases the gun cycles smoothly.

Is the hammer nose gettin stuck in the primer under the force of recoil or is something else going on? If so, would the fix be replacing the hammer nose?

Don’t know if it helps but I’ve included photos of fired cases and the hammer.

 

[Sudden Thunder]

Primers deeply indented by firing pin - try different primers, may possibly need to back the hammer spring tension screw back a turn

 

[mcb]

Make sure the end of your firing pin is free to move up and down around it's rivet. It does not need to move much bit need to be able to move some. Look to see if the end of the firing pin or it's hole in the recoil shield are damaged or have burrs.

 

[Col. Harrumph]

It looks to me that the tip (the business end) of the firing pin (aka "hammer nose") is damaged. Maybe it isn't just indenting the primers, but is embedding itself. Replacements are available and not a challenge to install.

 

[edwardware]

Fascinating!

The hammer should retract when you release the trigger; ensure that it does so consistently with an empty gun.

Assuming yes, it sounds like the hammer nose is getting stuck, which is pretty unusual. I would look to your recipe if those are handloads, and back off. I

Then make sure the hammer nose can rotate up/down a smidge on its rivet.

This'll be interesting!

 

[commygun]

This has happened with a variety of factory ammunition. The nose does pivot but the tip is very rough, almost chewed feeling.

 

[BBBBill]

The tip should be well rounded and smooth. You might try to clean that one up a bit to see if your situation improves, but plan to replace it.

 

[edwardware]

This has happened with a variety of factory ammunition. The nose does pivot but the tip is very rough, almost chewed feeling.

Likely the tip of the hammer nose is flame cut from a couple leaky primers. Having dressed a few over the years, I suggest:
- the finest abrasive you have, on the order of 1000 grit + (or I'd use a Spyderco Ultra-Fine tri-stone)
- on a rigid backer
- polish just enough to smooth the rough spots, change the shape as little as possible
- aim for round, not pointy

Looking at your fired primers, protrusion appears ok, so you might get away without replacing the nose.

 

[commygun]

So I dressed the hammer nose (the Sharpmaker stone is a great idea) and now the primer impressions are much closer to normal. However I think my original diagnosis was wrong. The revolver continues to bind about once or twice per cylinder-full.

As I noted above, I thought gently wiggling the cylinder was releasing the hammer nose from the primer. After shooting the gun today, I think the cylinder latch is moving under recoil. Wiggling the cylinder was just returning the latch to its proper position.
When the gun would bind today, I found that that gently moving the latch back and forth (not enough to swing out the cylinder) would release the binding. Sometimes I’d hear an audible click when this happened.
Does this sound likely to those of you who are knowledgeable about the internal workings of the S&W revolver?
Again, this only happens with live ammunition, so clearly recoil is a factor in whatever’s happening.

 

[243winxb]

On firing, the case head goes back & contacts the recoil shield. Normal.

If a dirty chamber or high pressure makes the fired brass sticky in the chamber, the brass will not slide forward as the cylinder turns. Brass must be free to move. If using moon clips, may add to the problem?

Jams things up. Happened 1 time on my M28-2, 357 mag, shooting 38 specials.

Compare case diameter near the head of new factory ammo to the fired diameter.

 

[243winxb]

The hammer should retract when you release the trigger; ensure that it does so consistently with an empty gun.

Yes it should, at least on my 1970s revolvers. Or not? https://www.thehighroad.org/index.php?threads/photos-of-the-insides-of-an-old-s-w.632115/ 1930 photos

The OP primers show healthy pressure. Not target loads.

If a reloader, invest in 45 Auto Rim brass.

 

[usaral63]

That hammer is supposed to retract, clearing the primer after ignition. Is it doing that, if not then the issue could well be some obstruction in the mechanism. Has the gun been tinkered with to lighten pull? Is there evidence of primer setback?

 

[commygun]

The revolver cycles flawlessly when dry-firing or loaded with expended cases. The binding can occur with moon clips or individually loaded rounds and it’s not confined to any one chamber.
If the cylinder latch spring has become worn or is otherwise fouled, is it possible that the latch is moving when the gun is fired, and can that movement tie up the gun?
From my observation the other day it certainly looks like that is what is happening (at least the part about the latch moving) but I don’t know if it’s possible for the latch mechanism to lock everything up. I can’t find a reference to this online.

 

[commygun]

Has the gun been tinkered with to lighten pull? Is there evidence of primer setback?

No evidence of primer setback. The double-action trigger pull certainly feels like any other S&W DA revolver that I’ve owned. Maybe a bit heavier than most.

 

[Col. Harrumph]

If the latch is moving muzzle-ward under recoil, which sounds really unlikely, it could (would) bind the hammer and prevent trigger pull. But to move forward at all it has to shove against a strong spring inside the cylinder arbor (axle). Thumbing the latch to the rear should free it.

Once the gun binds, does the trigger return to the rest position, and does the hammer rebound?

 

[commygun]

Once the gun binds, does the trigger return to the rest position, and does the hammer rebound?

The hammer does not appear to, hence my first thought that the nose was stuck in the primer. It’s locked up tight when the bind happens. The trigger usually returns to the rest position but not always. When it doesn’t it can easily be moved forward to the rest position. But that doesn’t unlock the bind. Only wiggling the cylinder or the cylinder latch seems to work.

 

[Jim Watson]

Sounds like a weak/cut/broken rebound spring, at least a place to start.

 

[Col. Harrumph]

Sounds like a weak/cut/broken rebound spring, at least a place to start.

Yup, it's time to lift the sideplate off and have a look (and post a pic). If you've never done that before, there's a right way and a wrong way. Youtube is full of howtos.

UPDATE: Holy cow, it's a miracle! I was fiddling with my 4" Victory model. I pushed the thumbpiece forward and then gently let it go, and it did not return to the rest position; it moved back part way and stopped. Trigger and hammer were bound up, and wiggling the cylinder freed whatever got stuck; the thumbpiece returned to the rest position (with a click) and voila.

Mine is a WWII revolver; the OP's is a 1917. This may be related to old school mechanics. One difference is that I don't have to fire the thing to make this happen. I wonder if the OP is unknowingly nudging the thumbpiece forward under recoil?

 

[commygun]

I wonder if the OP is unknowingly nudging the thumbpiece forward under recoil?

That is entirely possible. Look at that thumb knuckle with a shooting grip. Maybe the solution is a set of Pachmayr’s. I’ll pay close attention to that possibility the next time I shoot it.

 

[Riomouse911]

I had a Model 66-2 that had an issue with the cylinder release not working properly and the gun binding up when firing.

Before I went to S&W armorer classes I didn’t know what to look for or how to fix, so I sent it to S&W.

S&W replaced all the springs, cleaned up some gunk and sent it back. I think it was a combo of both issues, as it works great now.

Maybe start with a good internal cleaning and new springs? If it continues it may be other stuff.

Stay safe.

 

[1KPerDay]

good-looking gun

 

[commygun]

So just a quick coda to this problem. Took the revolver apart enough to remove the bolt. The revolver was surprisingly clean inside. Minimal schmeg, no rust.
Sure enough, the bolt plunger spring had somehow become partially crimped in its hole. I had to bend the very tip of a hypodermic needle to create a hook to drag the spring out of its confined space. Acquired a replacement and installed it. Took it the range and it ran with zero issues.
Thanks for all the input. Funny how my original diagnosis was so far off (though the hammer nose probably needed a little dressing regardless). And funny how a big old revolver can be rendered inoperable by a tiny spring.

 

[commygun]

Coda to my coda. Good Lord…

Took it to the range again yesterday and it started locking up occasionally again. However, I found that holding the thumb latch back slightly unlocked the hammer. Being now a little familiar with the internals from having replaced the spring, I realized the the bolt was not consistently being held back when the cylinder is closed, therefore blocking the hammer from cocking.

Whose job is it to keep the bolt pushed back?

The cylinder centerpin. And since this only happens when firing live ammo, I have to think that the recoil was jerking the centerpin back into the extractor housing (or whatever it’s called) and a weak spring or fouling was preventing in from bouncing fully back. Regardless, that allowed the bolt to rest fully forward, blocking the hammer.
I’m going to have to take the cylinder apart at some point, but today a little targeted lubricant and working the pin up and down apparently loosened it up. It was noticeably more protuberant after doing that. Took it back to the range, put 50 rounds through it, and it ran like a champ.

It’s a process when you’re guessing, fellas. I tell you what…

 

[Johnm1]

And we wonder why a gunsmith costs what they do. Those that learned this stuff in school earned their keep. Those that are guessing need the extra time.

It is fun to figure out this stuff. but if I had to charge $10/hr for my time every repair I did would be $1,000.