Different firing pins in two Mk II era 22/45s?

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FourCornerm'n
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Different firing pins in two Mk II era 22/45s?

Post by FourCornerm'n » Sat Jul 05, 2014 2:19 pm

My two Mark II era 22/45s have different firing pins? In more ways than one. Both guns were bought new at Salt Lake City gun shows in 2005

The blued firing pin from the slab barreled gun is 1 7/8" long. The stainless firing pin from the 5 1/2" stainless Target Model is only 1 9/16" long.

What concerns me more are the configurations at each end of these pins.

The longer blued pin's point of contact with the cartridge rim is tapered on both sides and the bottom, leaving a fairly thin wedged surface to hit the case rim. The back of this firing pin, where the hammer hits, is flat, with squared edges, and has the save width dimension as the the rest of the pin.

The shorter stainless pin's point of contact with the cartridge rim has no tapering, at all. It is almost perfectly square and its edges are squared. Its contact face with the cartridge case is almost four times larger than the blued firing pin's. At the back, instead of a flat, squared-sided surface for the hammer to hit, it is unevenly tapered with no squared edges or any corners. More metal is taken off from the upper left down towards the lower left. There's another, smaller cut on the lower left corner, and some on each of the right corner areas.

What the heck is going on here? I've fired this gun a lot. It looks like someone machined the wrong end of this firing pin? Plus, the FP is so much shorter, by design, that the interior of the bolt must be different, as well.

I was about to exchange the bolts between these two guns because the blued, long bbl'd slab side gun's bolt face is missing metal at and above the extractor. I should be able to do this, shouldn't I? Maybe not.

And whatabout the strange looking, shorter, firing pin in the stainless gun?

Whew!

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blue68f100
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Post by blue68f100 » Sat Jul 05, 2014 7:26 pm

Most FP for the 22's are like the first one you described with the tapered sides. This gives a better impact than being blunt. So you get better penetration. As far as length you may want to see how much of the pin sticks out when fully extended with stop installed. You do not want it too long to get in the face.

Can you tell if any of the FP been replaced with maybe VQ parts.
David

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FourCornerm'n
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Post by FourCornerm'n » Sat Jul 05, 2014 10:25 pm

Well, first off I have a broken firing pin. It's about 5/16" shorter than the one in the other gun and the surface is too rough to have been made that way. The front of the FP doesn't come close to the bolt face. Didn't set off a round when I took it the the range just now. It's the original pin, not a VQ replacement. Nice living 3 miles from a good range.

So, now I have a made to order, otherwise useless, shortened firing pin that I'll use to dry fire. Not really necessary because there's agreement here that not having any FP works as well for dry firing. (I got real nervous and backed off, however, when I earlier took the FP assemblies out and tried to close the gun. I couldn't get the mainspring latch to give me that slight spring pressure that's the sign everything's lined up correctly before I closed the latch. Don't want to go through that hassle again).

But, there's still a question, an academic one, about the firing pin because I'd installed it correctly - knew which was front and which end was back - and the back end of this firing pin is not squared - it has been worked all around as I described above. Not in the same symmetrical way as the FP from the other gun, but definitely worked, leaving a smaller surface profile The front end that strikes the case rim is gone - lord knows where. But why would the back end of this FP be so different than the squared dimensions of the back end of the FP from the other gun. Maybe this is a mistake.

In any case, I can now dry fire comfortably after closing the main spring latch without trauma. Will send for another firing pin to replace the shortened one.

(I installed the broken firing pin correctly - having the bottom lower lip facing forward to engage the FP spring assembly. So it is actually the back of this broken pin that is beveled almost as though it were meant to be the striking surface)

Dry firing question practically completely answered thanks to the broken FP.

Thanks

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Post by Bullseye » Sun Jul 06, 2014 8:55 am

All firing pins are made to the same dimensions over the generations of pistols. At one point, Ruger decided to change the profile on the firing end a little bit in an attempt to improve detonation over a wider range of cartridge brands. As for the one you have with the tapering on the back side, someone on the production line may have seen some flash from the stamping and touched it to a belt sander to taper the end and clean it up a little to remove any burrs. In any case that tapering won't negatively effect performance of the pin.

As to using the shorter one in your pistol for dry-firing... It is true you wont have a pin that will reach the breech face to damage it, but that pin will still beat up the firing pin stop if it is installed during practice sessions. Then when you place a correct length pin in the pistol it could possibly reach the breech face to cause some damage to the lip of the chamber.

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Post by FourCornerm'n » Sun Jul 06, 2014 4:24 pm

The best two choices then might be to remove the firing pin parts, keeping careful track of them while dry firing.

Or, to buy another FP stop pin, use the extra stop pin along with the broken firing pin.

The reason I may go with the second choice is that, with the firing pin out, I couldn't feel the spring tension in the mainspring just before closing the latch. This is usually a piece of cake. I manipulated things for several minutes but still couldn't feel the satisfying tension that let me know the hammer strut was in the right place. I put the FP assembly back in place, the normal tension before seating the main spring was there, and the latch closed successfully.


(There was a whole lot of deburring of the back of the stainless FP - maybe 20% all around).

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blue68f100
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Post by blue68f100 » Sun Jul 06, 2014 5:28 pm

Most of the fp stops that fail are soft. If you were to get a good harden pin you should be fine. Ruger at one time went to roll pins which did not hold up well but kept people form loosing them when the bolt was out. A good substitute is drill bit shaft but these can be soft too.
David

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