Weak firing pin on my 686?

Cerdan

Cerdan

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I was checking for sings of pressure on my spent casings today, after yesterday's range session. I noticed some "cratering" of the primer, and assumed this was a sign of high to excessive pressure, as I'd read in the Hornady reloading manual. However, the Speer manual says "Primer extrusion or 'cratering' is often incorrectly cited as being signs of excessive pressure. [...] In most cases, these are not pressure indications but rather gun problems. Extrusion can be due to excessive clearance between the firing pin and firing pin hole in the breech face or due to a weak firing pin spring."

After reading this, I was reminded of the fact that I had two or three misfires during the shoot. I assumed it was primer problems, but the rounds ended up firing after the second or third try. This is further indication of occasional weak pin-striking. Take a look at the picture below. Two examples of primer craters in the .357 primers, a normal-looking spent .38 primer on the lower left and a very weak pin-mark on the lower right.

primes.jpg


Does anyone have an opinion on this? Does my new toy have a weak firing pin spring?
 
Is the gun new or new to you as in previously owned? If the latter it is possible that somebody backed off the strain screw in an attempt to lighten the trigger pull(not uncommon, just wrong to do). If its a new gun thats a different story..
dB:)
 
Cerdan said:
yeah, it's new :(
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Just the same....take off the grips and check out the mainspring strain screw. It may have backed out. When my 625 was new the mainspring strain screw backed out gradually. I thought the trigger was getting better and better until one day I got intermittant light primer strikes. Worth a look.
It'd take you less than 5 minutes to check it.
 
For a minute there, you guys had me thinking it might be that simple, but the screw's screwed in as far as it'll go...

Any other ideas?
 
Cerdan said:
For a minute there, you guys had me thinking it might be that simple, but the screw's screwed in as far as it'll go...

Any other ideas?
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Bummer....is the gun clean? I have to ask. There's a little bushing where the firing pin goes through (hammer nose bushing). Check to see that there's no crud there that would cause it to bind.

add: could this be ammo related? If you're shooting reloads are the primers seated properly...
 
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Yeah, it was clean, as the problems happened the very first time I took it out to the range, and the second time, after I gave it a good scrub (including on the breech face).

...My first thought was that it was ammo related in some way. I shoot both factory and reloads, but I check every round, and there weren't any improperly seated primers, as far as I could tell... And the fact remains that some rounds do show a very weak pinstrike, as pictured above.

At this point I'm thinkin' weak firing pin spring, but what do I know?
 
What do you see happen when you dry fire it? Do you have another gun to compare it to? There's a number of components that come into play, like the transfer bar / safety system. Typically if you dry fire it double action, the hammer drops quite far, you let off the trigger and the hammer comes back up a little. You can also take off the grips and the side plate and watch the movement of the parts. Too bad you don't have access to a good pistol smith. He could diagnose that pronto and check out other specs of the gun that might need fine tuning.
 
I don't recommend removing the side plate unless you have a good idea of what you're doing. I wouldn't do it to one of my revolvers but I don't know anything more than the obvious. Your gun is new. Call the store where you bought it or bring it to them. It's a warranty issue.
 
Your right. I get carried away with my own troubleshooting. Anything he does potentially they will blame him as the cause. Good advice misfire. Get a handfull of the lightly struck primer cases and send them in with the gun.
 
Actually, three of those primers look normal to me - the .357's look like just about every 357 I've ever fired, the first 38 looks like a standard velocity 38 (38 +P look like the 357's) the last one does look like a light strike. Is it possible that this round was fired single action? Single action strikes are lighter because the hammer falls a shorter distance. If you experience light strikes (FTF's) in a new revolver you should have it dealt with under warranty.
 
ian_in_vic said:
Is it possible that this round was fired single action? Single action strikes are lighter because the hammer falls a shorter distance.
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It's actually the opposite--the hammer fall is shorter in a double action pull.

Oh, and good call on not removing the sideplate--if you don't know the correct procedure you could end up bending it.
 
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