Colt D frame Hammer mounted Firing Pin Replacement

[41022collector]

Hey all...... for the first time in my 23 years of gunsmithing I have to replace a Colt "D: frame Cobra, Hammer Mounted firing pin. I have replaced and fitted hammers and such, but never just the firing pin and rivet. I am competent, but I am procedure and correct way of doing things driven and do not want to have to do this twice or have to replace the hammer due to my mistake, so I am asking for advice.

It seems as though a HOME Smith tried to lighten the primer impact of the pin and ground down the pin to the point it does not even come through the frame hole, much less touch the primer.

NOTE: Yes, I verbally throttled the customer into never doing home smithing again and to give his dremel tool away.



The hammer and the rivet it is installed with are BRUSHED finish to blend the rivet to the surrounding hammer metal.

1. Is there a direction in which the rivet normally flows ie left to right or right to left?

2. Recomendations on blending hammer to pin flush finish, method, wire or stone or both?

3. Can a snug fitting roll pin be used rather than the rivet and then use a rol pin set punch (I would imagine the roll pin segment line would go directly 180 degrees of the direction of the hammer?)?

4. Does anyone have a link to a Colt D frame, hammer mounted firing pin replacement procedure or can copy it to me in a cut and paste?

You can get ahold of me here or at [email protected]

Regards,
Mike

 

[Oyeboten]

Hi Mike,


I have wondered similarly...but have not replaced any Colt Firing Pins, nor spoken about this to anyone who has, to know.


Is the Rivet Hole slightly 'Hour Glass' Shaped, or plain/parallel?


Is the old Rivet to be merely driven out, or, Drilled, and the then thin shell cut or bent 'in' with a narrow Chisel or Graver and removed?


Is the Factory replacement Rivet longer than the width of the Hammer, anticipating upsetting, grinding/Fileing to flush?


Roll-Pins being straight-parallel-cylindrical, should be fine in a straight-sided hole.



Looking forward to hearing about what you find out on this.




Phil

 

[MMCSRET]

The Kuhnhausen book "Colt Revolvers Vol.1" details tha procedure.

 

[Jim K]

First, you have to remove the hammer from the frame and set it up in a copper or brass jaw vise or better on a bench block. Then you have to locate the cross pin and drive it out, left to right. Use a flat face punch On some guns it is quite hard to even locate the pin, since the hammer was polished after its installation. If using a vise, make sure the hammer is well supported; the Colt hammer is very thin just below the head and you can easily break the hammer while trying to drive out the cross pin.

Once the pin is out, replacing the firing pin is easy, but I recommend an additional step. Make a new pin just a tad smaller than the regular pin so it is a tight slip fit. Using it, install the firing pin in the hammer, reassemble the gun and make sure everything works and that protrusion is correct. This makes sure you have the right firing pin and that it won't bind anywhere on the frame. Then remove the hammer again and install the correct pin and firing pin.

Some writers call the pin a rivet, but it really is not in the sense that the S&W rivet is. The Colt pin is a drive fit, and can be expanded by peening, but it really is not a rivet in the normal sense. Once the pin is solidly in place, it can be peened if desired, then the hammer polished to again blend in with the pin. There is no special trick to polishing the hammer, I always used the same wheel we used for the final polish before bluing. If the pin is a bit high, a flat file or fine emery paper will take it down before polishing.

If you can install the pin with the same degree of "invisibility" as the factory, congratulatons. Some gunsmiths don't bother; they bevel the ends of the pin so its presence is obvious, thinking that looks better than a possibly botched attempt to hide it.

IMHO, a roll pin would look like heck on one of those guns.

Jim

 

[41022collector]

Oyeboten: I took an old colt hammer and took the old pin out by a drift punch and press.and then ran the hammer on the CMM. The hole in the hammer is parallel and not tapered. The new rivet pin is straight, although oversized by .00037.

MMCSRET: I am searching for the Colt Book and will damn well charge the customer for it LOL

Jim, thank you very kindly for the How To, it helped alot. I believe I will bevel the edges of the new pin and not bother with the brushed finished...... * I am still hot under the collar at this guys attempt with a dremel to solve a problem that was not even there.

Regards,
Mike

 

[Jim K]

Just FWIW, I know the hole is not tapered and the pin is straight (it is a drive fit), but a lot of folks on here go nuts if I say it can come out either way because they read someplace that all pins have to come out left to right. Since it doesn't matter a rat's tail end, I have come to say that just to spare the "l to r" fringe the trouble of "correcting" me. Kuhnhausen calls it a rivet, even though it is not.

Good luck.

Jim

 

[Old Fuff]

Kuhnhausen calls it a rivet, even though it is not.

The very last (and seldom seen) D-frame revolvers did have hammers with a hollow rivet to hold the firing pin. Kuhnhausen took a lot of his stuff out of Colt's in-house manuals, and for that reason may have used the word "rivet."

However a solid pin is more often encountered, and your instructions in that case are dead-on.

 

[Oyeboten]

41022colletor,


Interesting and useful info...

If it was me, as for general overview, general thinking, I'd consider to lay the Hammer on a flat Steel Block or heavy Plate, aligning the position of the 'Pin' or 'Rivet' with a small hole in the Block or Plate...in order to avoid any bending-stresses in the Hammer for the drive-out or interference-fit press-in procedures.


To my mind-

If the 'Pin' is pressed in loose or snug and then expanded by Peening, it seems reasonable to me to call it a Rivet.

If the Pin is a tight Arbor-Press fit, and not expanded by Peening, then it seems reasonable to call it a 'Pin'.

Possibly, it can be either, depending...



The S & W Roll-Pin or Shear-Pin, to me, seems unambiguously a 'Pin' and not a Rivet, by virtue of it not being expanded or upset by squeezing or Peening.

Now I've sent off for the two volumes of the Kunhausen Colt Revolver Books, thanks to your Thread.


Phil

 

[Old Fuff]

The S & W Roll-Pin or Shear-Pin, to me, seems unambiguously a 'Pin' and not a Rivet, by virtue of it not being expanded or upset by squeezing or Peening.

You'd be right, except the S&W hollow rivet (pin or whatever) is expanded on both ends...