Model 29-2 Misfire

[robmoss]

Hi all and thanks for listening to me cry about my Model 29.

Last week I bought a used model 29-2 from a reputable Dealer. The next day I took it to the range; squeeze and...click. Mmmm. Check the round and I see a small dimple in the primer. Fresh round. Squeeze and.... click. Dimpled. Damn. Fresh round. Squeeze and.... BOOOM! Fresh round. Squeeze and.... click. You get the idea I am sure.

All in all I have 5 rounds that fired and they all fired first time. 3 are Winchester and 2 are Magtech. The fired cartridges do have proper dimples in the primer, but then I am wondering if that might be due to the round pushing back on the hammer nose as the bullet leaves the case.

I also have 7 rounds with very small dimples in the primer that did not fire, 2 Magtech and 5 of my own reloads.

OK so I just used the r word. I have reloaded 44 for some years now and shot them all in my Blackhawk with never a misfire, not one.

If I dry fire and look at the the hammer nose through the cylinder/backplate gap I see that it barely crosses the gap so I am wondering if that is the issue.

I returned to the dealer to ask some advice and I did not get the reception I expected. My question was going to be, "Do you think I should replace the hammer nose, the main spring, or both?" They had at least two other M29-2s that we could have done a quick comparison with but all I got was "Reloads... blah, blah... probably won't work with all ammunition... blah, blah... what do you want us to do about it?" Not what I expected a week after they happily took my money, but then maybe I came across wrong.

So I am now going to stop bleating and simply ask this assembly of gurus the question I was going to ask the dealer. Should I replace the hammer nose, the mainspring, or both?

I am sure that there is a wealth of knowledge on this site and I thank you in advance for your advice.
If you would also like to correct my understanding, expectations or attitude please feel free to do so.

Best regards,

Rob in Texas.

 

[cmort666]

1. Check the strain screw on the front of the grip frame. Is it screwed all the way in? Some people partially unscrew it, thinking it will make the trigger pull "lighter". What it does is make ignition unreliable. Make sure it's screwed all the way in.
2. If the strain screw is screwed all the way in. Compare it with a known good, UNALTERED screw. The 3" Model 65 I bought from CDNN experienced almost identical misfires to yours. Someone had SHORTENED the strain screw so that it would bear on the mainspring less heavily, even when it was screwed all the way in. Once it was replaced with a stock screw, the problem disappeared.
3. Check the mainspring. Is it corrugated, with a raised rib up the center? I had similar issues with my Model 14. While apparently stock, the strain screw in the gun was just short enough (wear?) to slip around on the rib, causing misfires. Again, a replacement strain screw solved the problem.
4. What type of primers are you using? For match loads I use Federal match primers. They're softer than other brands, especially CCI.

Try those things.

 

[Alk8944]

As mentioned, the first thing to check, and most likely to cause mis-fires, is a loose strain screw. If you tighten the strain screw and still have mis-fires with factory ammunition then replace the mainspring with a new factory spring. If you still have a problem then replace the strain screw. The strain screw and a new spring will probably be lsee than $10.

Contrary to cmort's comment, if you find a mainspring that has a raised rib down the middle that is not a factory spring but, rather, a Wolf "Power-Rib" after-market spring. While there are several after-market parts providers I have never been convinced that any of their products are of any higher quality, or offer better performance that S&W factory parts.

First source of S&W parts is, surprise, S&W. Call Customer Service an 800-331-0852.

If you don't know where to locate the strain screw, remove the stocks if they cover the front of the grip frame. The strain screw is located toward the bottom of the front of the grip frame.

 

[cmort666]

Contrary to cmort's comment, if you find a mainspring that has a raised rib down the middle that is not a factory spring but, rather, a Wolf "Power-Rib" after-market spring. While there are several after-market parts providers I have never been convinced that any of their products are of any higher quality, or offer better performance that S&W factory parts.

I never stated that it was a "factory" spring, only that, combined with a strain screw of marginal length, it could cause unreliable ignition. And in fact, that's exactly what it did in MY gun.

 

[cochise]

Endshake can cause a problem also. Older 29's have been shot loose over the years and look ok but are not in spec. Check with the hammer cocked and thumb on top, cock and release, while keeping yopur trigger finger on trigger. Check for back and forth movement on the cylinder, all 6 chambers. Too much play will cause a mis fire. I don't remember the exact tolerance allowed, sorry . Maybe Alk8944 can help us out on that,

 

[RonH]

I had the same issue with my model 28. It was misfiring and I called Smith & Wesson to get information on returning it. I was advised to check the strain screw 1st, and found that it was backed out a little. I tightened it up and no more misfires! It wasn't backed out all that far either.

 

[all357mag]

Mainspring screw and seating depth of primers.

 

[loknload]

I learn something new here all the time!
I've never experienced this problem but if I ever do I'll know what to look for thanks to you guys!

 

[cmort666]

I learn something new here all the time!
I've never experienced this problem but if I ever do I'll know what to look for thanks to you guys!

I never expected it, but have seen it in THREE of my S&W revolvers. The least expected was the shortened screw. I didn't see that one coming and it baffled several people until it occurred to me.

 

[Sebago Son]

If the strain screw is tightened all the way and you still are getting misfires you may want to try this.... take a FIRED, SPENT primer, pry out the anvil, use it as a cup shim between the end of the strain screw and the main spring. Won't cost you a penny and you won't have to wait for a new strain screw to arrive.

 

[cmort666]

If the strain screw is tightened all the way and you still are getting misfires you may want to try this.... take a FIRED, SPENT primer, pry out the anvil, use it as a cup shim between the end of the strain screw and the main spring. Won't cost you a penny and you won't have to wait for a new strain screw to arrive.

I wouldn't consider that a "fix", but it certainly strikes me as an excellent diagnostic tool.

 

[Marshall 357]

How about a picture of that 29?

 

[robmoss]

You read my mind. Pics would be good. I just hope they uploaded properly.

I have checked the strain screw and it is bottomed out, won't go any further. I don't know if it is specification length but it is all the way in.

I am thinking of dropping $20 on a new mainspring, hammer nose and hammer nose pin from S&W, and here is why.

The mainspring is cheap and let's replace it after 30 years coz it's cheap.
The hammer nose because the picture shows that it makes it through the hammer nose bushing hole and not too much further.

I took the cylinder out so you could see more clearly, but with the cylinder in I can see that it just makes it into the chamber, but only just. The chamber mouths are rebated so the base of the cartridge sits flush with the back of the cylinder, not proud.

One more thing to note is that the hammer front is hard up against the frame and will not travel any further forward. I took off the side plate to make sure this was the case just in case you are wondering.

So what do you think?

Let me know if you would like any more pictures, and thanks for the advice.

Best regards,

Rob in Texas.

 

[robmoss]

In reply to cochise' point about endplay I tried to move the cylinder up and down just like you described. I can feel it move as I pull down and if I look I can maybe, maybe, see it move ever so slightly. I can here it too, but only a small noise. I have no idea of the spec either but it would make sense to me that a little play is what you want. Like I say, I can't see a big movement and I have to pull fairly hard to get the cylinder to move back.

Thanks again.

Rob in Texas.

 

[Alk8944]

I tried to move the cylinder up and down just like you described.

Rob,

What you need to check is not radial movement (up/down/sideways) but axial, fore and aft relative to the cylinder axis, freeplay. It shouldn't exceed .003", preferable just enough to tell there is some, if any. Measure this with feeler gauges in the barrel-cylinder gap with the cylinder pushed forward and then pulled to the rear. The difference between the two measurements is end-shake. There has to be a lot of end-shake to cause mis-fires.

Your photos show completely adequate firing pin protrusion, this isn't the problem.

 

[robmoss]

Hi Alk8944,

By up and down I do mean along the axis of the cylinder. I am guessing by what you said that I am good, but I will pull the feeler gauges out and check for sure. I am stunned that there is enough pin protrusion, I was so sure that it was not enough.

I have the info for a Main spring and hammer nose, so I will order those up on Monday. At the price I might as well order more than I need. I will change the Main spring first and then test before changing the nose.

Thanks for the advice.

Best regards,

Rob in Texas.

 

[cmort666]

I have the info for a Main spring and hammer nose, so I will order those up on Monday. At the price I might as well order more than I need. I will change the Main spring first and then test before changing the nose.

If you're going to order those things, you might as well spend a little more and get a strain screw.

 

[amazingflapjack]

Check the head spacing and cylinder/forcing cone clearances as a couple posters suggested.