Gman

Firing pin length

9 posts in this topic

Does anyone have the data for the design length of the firing pin?

I measured mine because I had another "double fire" with Ugly Betty. Assuming that my mic is correct, her pin length is 5.562" while the pin on my B series is 5.545". I realize this is only a .017" difference, but you never know. The firing pin spring retainer was still in place, so that wasn't the problem

Thanks

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Gman, I don't know the correct length of the firing pin right now, but try replacing the firing pin spring. A weakened firing pin spring can make a world of difference. Also make sure that there is no binding of the firing pin that would lead to a stuck pin scenario.

By the way, I NEED a firing pin retainer with the little clip attached. I hope someone has an extra. Thanks.

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Hey Tanker: GunParts corp had some a while back, have you tried them? By the way the little clip is not necessary, just hold the retainer in place until you slip the rear into the bolt. The bolt holds it at that time. :D

Have a good 4th buddy!!

Ryche

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Thanks, Tanker. The spring seems to be OK when compared to a new one I bought last year.

However, while rotating the firing pin by hand and working it back and forth in the bolt, I did find some binding. I then checked the firing pin for run-out using a case gauging tool that I have. I found the forward half of the firing pin to be bent causing the pin itself to wobble about an eighth of an inch which caused the binding.

I can only guess that this was caused by someone using high powered ammo instead of M2 ball - or maybe the pin is, in fact, too long. Using my bench vise to support the lower half of the firing pin I was able to straighten it out by hand. Run-out now measures zero. I'll try it out at the range tomorrow.

Happy 4th to everyone.

Semper Fi

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Thanks, Tanker. The spring seems to be OK when compared to a new one I bought last year.

However, while rotating the firing pin by hand and working it back and forth in the bolt, I did find some binding. I then checked the firing pin for run-out using a case gauging tool that I have. I found the forward half of the firing pin to be bent causing the pin itself to wobble about an eighth of an inch which caused the binding.

I can only guess that this was caused by someone using high powered ammo instead of M2 ball - or maybe the pin is, in fact, too long. Using my bench vise to support the lower half of the firing pin I was able to straighten it out by hand. Run-out now measures zero. I'll try it out at the range tomorrow.

Happy 4th to everyone.

Semper Fi

Gman, I'm glad to hear that you did find a fixable problem. I hope that the straightened firing pin cures the problem. I mentioned it because I had a similar problem with another rifle....a slightly bent firing pin caused me hours of diagnostic tinkering.

:D Happy Birthday United States Of America :D

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The firing pin in mine was binding as well. I was able to straighten it, but went ahead and purchased a spare just in case. Apparently it had been that way for a while by looking at the wear. I'll have to compare the length of both.

So what would cause a bent firing pin??

Sure enough,they are different lengths. The one currently in is D4550 and the slightly longer replacement is 5932. It is interesting though, that D4550 has 2 sets of the indents that the collar is squeezed into. Mind you I'm eye balling these, but from one end to the other, everything is just a knat's eyelash off.

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Well, here is the report from the range. I put about thirty rounds through her without a double. Before going, I shortened the pin by .007" (still .010 longer than my other one).

It finally occurred to me to check something that I read about on a Garand website a couple of years ago. Load two, fire one and then check the primer. Sure enough the primer was dimpled. So I still think this firing pin is too long.

Thanks for everyone's input. Any other ideas, or does someone have access to the working drawings so that the design length can be determined?

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It may be a non-problem. AR-15s and M-16s , well at least the ones from 20-30 years ago , did the same thing as par for the course. It was only a problem with some brands of primers. I have never checked the Johnson for this , so I don't know if it's SOP or not.

Chris

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Thanks, Emmagee. When this first happened, it appeared to me that the design of the bolt and its camming action would prevent the firing pin from protruding through the bolt face upon closing. However, this appears not to be the case with this rifle. My other Johnson has never doubled on me so that led me to check the firing pins against each other finding that this one was visibly longer.

I put in a new firing pin spring and went back to the range today. The pin still dimpled the primer after firing. I also had taken my whetstone and after several cycles of fire, check, strip, stone, reassemble and repeat, I got the pin just the right length. It no longer leaves a mark on the primer when cycling. Ugly Betty now shoots well (one at a time), tosses the brass about six feet away and doesn't destroy the cases anymore. Life is good.

Regarding primers, as you probably know, Springfield specifies military ammo because of its hardened primers. When I reload for my semi-automatics, I always use CCI #34 primers as the company says they are mil spec.

Semper Fi

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