S&W Revolver Problem-- pierced primers, not due to pressure

[kuduman]

OK, sy my M29 has started piercing primers, and it's not due to pressure. Cases fall out, well within book limits (I'm not remotely trying to hotrod the loads-- I hate the full power loads), primers look good, except for tiny holes appearing in the crater.

Looking closely at my hammer-mounted firing pin, it has a crater in it. I do not know if this is new. I have run a hard stone over the pin to remove any burrs.

So... am I using thin primers (Rem 2.5), seating them high (possible; got lazy and switched from an RCBS to a cheap Lee primer seater), do I have a damaged firing pin now, or something else?

This started today, and pretty well messed up my load development. But something has changed-- loads (.44 SPL class loads) that I've fired hundreds of without issue are now piercing. Little pinholes in the primer crater-- just blackening the crater. Had about four of these out of 50 today.

I'm guessing that I need a new firing pin. Any known-experienced S&W smiths in the metro area? I don't want to pay for OJT. I have guns where I am willing to fund OJT, but this is not one of them.

 

[Horsehat]

Pics of the firing pin?
Seating the primers inadequately would not likely cause this, the strike would just completely seat the primer with possible erratic ignition. Have you changed primer brands or even lots with this loading? Are the flash holes in the fired cases excessively large?

 

[Wheeler]

Sounds like endshake. The cratering of the firing pin is most likely due to it being inside the primer during ignition.

It's possible the frame and/or the hammer have peened creating a tolerance issue but I'd have a competent revolver smith look at the endshake tolerances first.

 

[fifthhorsm]

retired gunsmith..... seen plenty of firing pins with tip damage. all it takes is a couple of bad primers piercing and the damage is done, the hot gases can cut steel very easy.... you said you had a stone..... go ahead and try to stone it out, probably 9 times out of 10 it will work. first just stone the tip flat to get thru the damage then round it like the original profile but do use a hard Arkansas stone, you don't want to remove too much too fast. most of the time the damage looks far worse than it really is. most of the time only have to take off about .005 to clean it up. if you can stone it away you'll be good to go. take too much off and you will know.... it won't fire LOL if that happens then just replace the firing pin, cheap and easy to do. and most important don't listen to all the other bs people will suggest. surprised they haven't told you that you need to replace the springs LOL the only way the tip gets cratered is by gas cutting from a pierced primer.

 

[Jackie Graham]

Did you recently change the primers you use? Are you using Magnum primers. Magnum primers have a thicker cup. Using standard primers or bad primers might have started the issue. As state above once the problem starts you will either have to smooth out or replace the firing pin. However, if you continue to see the issue after smoothing out the firing pin you need to look at getting rid of that batch or primers.

JMO

 

[DinkyDau]

It may be just a seating problem with the primer install tool..Have you shot a factory load, to see if does the same thing?

 

[kuduman]

It may be just a seating problem with the primer install tool..Have you shot a factory load, to see if does the same thing?

Ah, no-- I can try that, but I don't keep them around. Much cheaper (and easier on the wrists) to load 'em myself.

 

[kuduman]

Did you recently change the primers you use? Are you using Magnum primers. Magnum primers have a thicker cup. Using standard primers or bad primers might have started the issue. As state above once the problem starts you will either have to smooth out or replace the firing pin. However, if you continue to see the issue after smoothing out the firing pin you need to look at getting rid of that batch or primers.

JMO

I have not changed primers, but am using Rem 2 1/2, just LP, not magnum primers. I have large magnum primers, or can get them. That might help, but if it's firing pin damage I need to fix the underlying cause.

 

[DinkyDau]

Ah, no-- I can try that, but I don't keep them around. Much cheaper (and easier on the wrists) to load 'em myself.

Agreed but if you want to eliminate a question to a problem, Pick up some 44 special...That way you can be sure

 

[kuduman]

retired gunsmith..... seen plenty of firing pins with tip damage. all it takes is a couple of bad primers piercing and the damage is done, the hot gases can cut steel very easy.... you said you had a stone..... go ahead and try to stone it out, probably 9 times out of 10 it will work. first just stone the tip flat to get thru the damage then round it like the original profile but do use a hard Arkansas stone, you don't want to remove too much too fast. most of the time the damage looks far worse than it really is. most of the time only have to take off about .005 to clean it up. if you can stone it away you'll be good to go. take too much off and you will know.... it won't fire LOL if that happens then just replace the firing pin, cheap and easy to do. and most important don't listen to all the other bs people will suggest. surprised they haven't told you that you need to replace the springs LOL the only way the tip gets cratered is by gas cutting from a pierced primer.

OK-- that sounds good. I'll measure the protrusion and see if I can't clean it up. More worried about re-rounding it than anything else.

And I'll measure the end-shake while I am at it.

EDIT: OK, that cleaned up in about five minutes. Protrusion still looks to be 30 thousandths plus, and the crater is gone. I don't know if I've changed the shape much if at all. I'll find out Wednesday at my next range opportunity. Thanks!