Colt Cobra broken firing pin

Cumminspwrd02 · October 26, 2009, 06:28 PM

Ok, I have a colt cobra 38 special revolver that was handed down to me from a family member. I've had the gun about a year and have shot maybe 150 rounds through it since I have owned it. By the serial number it was made in 1972 and my great uncle had owned it since it was new. I don't know how much he shot through it and I can't ask him since is ins't with us anymore.

My problem is I went to fire a couple rounds through it recently and on the first shot the gun failed to fire. I unloaded it and then inspected the gun to find the firing pin had broken. I looked over the broken piece of the pin and the rest of the pin still on the gun to find it was worn some. I also ispected the rest of the gun and it seems to be in good shape. Since I've owned it I have kept it cleaned and lubed, before I owned it...I dunno how my great uncle cared for it.

Is the firing pin for a Colt Cobra easy to find? Is it something I can change out or should I just have a gunsmith do the work? I am pretty confident I can do it, I'm a mechanic/machinist. Would it involve any special tools?

Thanks!

Dfariswheel · October 26, 2009, 07:11 PM

Change out is as follows:

Disassemble the gun and remove the hammer.
If you really want to do this yourself, be smart and invest $33.00 in the Jerry Kuhnhausen book, "The Colt Double Action Revolvers: A Shop Manual, Volume One".
http://www.brownells.com/.aspx/pid=2..._A_SHOP_MANUAL

This is a real gunsmiths manual detailing 100% disassembly and ALL gunsmithing operations on the Colt revolvers.
It shows firing pin replacement.
This is the best money a Colt revolver owner can spend.

Locate the rivet in the hammer.
This is polished flush so it can be tough to see, but you can usually spot it.

Put the hammer on a bench block with a hole that will pass the rivet and use a punch to carefully drive the rivet out.
Be careful. The idea is to drive the rivet out without scarring the sides of the hammer or enlarging the rivet hole. The more you scar the hammer sides, the harder it is to hide the new installation.

Use a carbide ball bit to lightly countersink both sides of the hole in the hammer.
This gives the new rivet room to spread, but still leave a strong rivet after finishing.

Install the new firing pin and insert a new rivet.
Use a small hammer to carefully rivet one side of the rivet, then flip over and rivet the other.
The firing pin MUST be free to rotate up and down in the hammer body, so don't over do it. You just want a good rivet on both sides with a freely moving firing pin.

Use a file or abrasive grinding tip to careflully remove most of the excess rivet heads, then use abrasive cloth on a piece of heavy plate glass to polish both sides of the hammer until the rivet is flush with the hammer body and is hard to see.

Make sure the new firing pin has protrusion through the frame of .042" minimum and .056" maximum in the Cobra .38.
Clean up and the job's done.

Buy new firing pins and rivets here. The Colt .38 Cobra uses the same firing pin and rivet as the Diamondback, Detective Special, Police Positive Special, and Agent.

Gun Parts Corp only have rivets.

http://www.jackfirstgun.com/

http://www.gun-parts.com/colt/

http://www.parts4guns.com/
Click "COLT" and WAIT.
Part FP-CF, D-frame, 56103 $8.00

http://www.coltparts.com/index.html

Cumminspwrd02 · October 26, 2009, 08:04 PM

Dfariswheel, thanks for the reply and information. I have been planning on getting a manual for this gun for a while now, just haven't yet. Looks like something I can do without any problems with my background. I am going to locate a new firing pin and rivet for it. aside from doing the pin is there anything else I should replace or do while I have the gun apart?

Dfariswheel · October 27, 2009, 05:50 PM

Clean and fresh lube.
I recommend a little grease on the trigger and hammer interfaces for a smoother pull.
Unless there's a good reason to do so, I'd leave the bolt and screw in place, and I wouldn't attempt cylinder disassembly unless you have a later model.
The earlier models require a couple of special tools.

I wouldn't try bending the mainspring unless you have a good trigger gage, because its way to easy to get reliability issues if you just try putting a bend in blind.

October 26, 2009, 06:28 PM	#1
Cumminspwrd02 Member Join Date: March 29, 2009 Location: Indiana Posts: 33	Colt Cobra broken firing pin Ok, I have a colt cobra 38 special revolver that was handed down to me from a family member. I've had the gun about a year and have shot maybe 150 rounds through it since I have owned it. By the serial number it was made in 1972 and my great uncle had owned it since it was new. I don't know how much he shot through it and I can't ask him since is ins't with us anymore. My problem is I went to fire a couple rounds through it recently and on the first shot the gun failed to fire. I unloaded it and then inspected the gun to find the firing pin had broken. I looked over the broken piece of the pin and the rest of the pin still on the gun to find it was worn some. I also ispected the rest of the gun and it seems to be in good shape. Since I've owned it I have kept it cleaned and lubed, before I owned it...I dunno how my great uncle cared for it. Is the firing pin for a Colt Cobra easy to find? Is it something I can change out or should I just have a gunsmith do the work? I am pretty confident I can do it, I'm a mechanic/machinist. Would it involve any special tools? Thanks!

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October 26, 2009, 07:11 PM	#2
Dfariswheel Senior Member Join Date: May 4, 2001 Posts: 7,478	Change out is as follows: Disassemble the gun and remove the hammer. If you really want to do this yourself, be smart and invest $33.00 in the Jerry Kuhnhausen book, "The Colt Double Action Revolvers: A Shop Manual, Volume One". http://www.brownells.com/.aspx/pid=2..._A_SHOP_MANUAL This is a real gunsmiths manual detailing 100% disassembly and ALL gunsmithing operations on the Colt revolvers. It shows firing pin replacement. This is the best money a Colt revolver owner can spend. Locate the rivet in the hammer. This is polished flush so it can be tough to see, but you can usually spot it. Put the hammer on a bench block with a hole that will pass the rivet and use a punch to carefully drive the rivet out. Be careful. The idea is to drive the rivet out without scarring the sides of the hammer or enlarging the rivet hole. The more you scar the hammer sides, the harder it is to hide the new installation. Use a carbide ball bit to lightly countersink both sides of the hole in the hammer. This gives the new rivet room to spread, but still leave a strong rivet after finishing. Install the new firing pin and insert a new rivet. Use a small hammer to carefully rivet one side of the rivet, then flip over and rivet the other. The firing pin MUST be free to rotate up and down in the hammer body, so don't over do it. You just want a good rivet on both sides with a freely moving firing pin. Use a file or abrasive grinding tip to careflully remove most of the excess rivet heads, then use abrasive cloth on a piece of heavy plate glass to polish both sides of the hammer until the rivet is flush with the hammer body and is hard to see. Make sure the new firing pin has protrusion through the frame of .042" minimum and .056" maximum in the Cobra .38. Clean up and the job's done. Buy new firing pins and rivets here. The Colt .38 Cobra uses the same firing pin and rivet as the Diamondback, Detective Special, Police Positive Special, and Agent. Gun Parts Corp only have rivets. http://www.jackfirstgun.com/ http://www.gun-parts.com/colt/ http://www.parts4guns.com/ Click "COLT" and WAIT. Part FP-CF, D-frame, 56103 $8.00 http://www.coltparts.com/index.html

October 26, 2009, 08:04 PM	#3
Cumminspwrd02 Member Join Date: March 29, 2009 Location: Indiana Posts: 33	Dfariswheel, thanks for the reply and information. I have been planning on getting a manual for this gun for a while now, just haven't yet. Looks like something I can do without any problems with my background. I am going to locate a new firing pin and rivet for it. aside from doing the pin is there anything else I should replace or do while I have the gun apart?

October 27, 2009, 05:50 PM	#4
Dfariswheel Senior Member Join Date: May 4, 2001 Posts: 7,478	Clean and fresh lube. I recommend a little grease on the trigger and hammer interfaces for a smoother pull. Unless there's a good reason to do so, I'd leave the bolt and screw in place, and I wouldn't attempt cylinder disassembly unless you have a later model. The earlier models require a couple of special tools. I wouldn't try bending the mainspring unless you have a good trigger gage, because its way to easy to get reliability issues if you just try putting a bend in blind.