Colt Police Positve Special misfiring

[BSA1]

I have a Colt Police Positive Special 1970’s production that is occasionally not firing and binding up. It is driving me nuts because I can not replicate the problem. The gun is excellent condition on the exterior.

It has two issues going on at random;

The first one is the hammer will move partway back and then lock up when being trigger cocked for double action shooting. The hammer will not move any further back. Releasing the trigger and pulling the trigger again and it functions fine.

The other issue is it is occasionally hitting the primer way off center causing misfire.

I have been using my reloads so today we used a box of factory UMC for control ammo and my old Model 10 for the control gun. All of them fired the first time with no problems. The problem occurs with my reloads. I am using Winchester Small Pistol primers. For the record I have reloaded many thousands of this particular bullet, primer, powder combination. I tested the box of reloads that were causing problems in the Colt in my Model 10 and everyone fired without a hitch.

The gun functions fine most of the time when empty. It locks up perfectly double and single action. None of the primers on my reloads feel high and the cylinder spins easily when loaded. I have only been able to get the action to lock up once when dry firing. I did that by trigger the hammer partway bad, slightly releasing the trigger, then resuming the trigger cocking.

I have not disassembled this gun and have only cleaned the action by spraying oil into it.

I have never tried disassembling the action on a Colt Double Action revolver. However I have disassembled and worked on S&W revolvers many, many times. I have J.B. Wood’s book on revolver disassembly.

Ok.

What are some of the possible causes?

Any special issues with disassembly of this Colt?

Show and tell pictures;

Fired 50 rounds of UMC factory ammo.



One round (worst one) reload with firing pin barely hitting the edge of the primer.

 

[BBBBill]

Sounds like a timing issue. The Colt D/E/I frame revolvers are nothing like the S&W revos. I've done S&Ws so many times I can disassemble one blindfolded. Same with Rugers, 1911s, M4, M-16, M-1, M-14, and the later Colt V and AA frame revolvers. Those early Colts scare me.

 

[rcmodel]

Misfires in a Colt:
See this thread about something similar I went through, and break out the calipers.

http://www.thehighroad.org/showthread.php?t=563715&highlight=Colt+commando

Locking up totally when cocking the hammer DA/SA:
That is a timing issue and beyond the scope of what I can tell you about Colt timing in this thread!

I would recommend the Kuhnhausen book and delve into the mystery's yourself if you fell lucky.
http://www.midwayusa.com/product/36...shop-manual-volume-1-book-by-jerry-kuhnhausen

rc

 

[Jim K]

Yes, it sounds like the lower "finger" of the hand is failing to engage the ratchet; instead it is hitting on the edge of the ratchet tooth and hanging up. That is probably also related to the failure of the cylinder to carry up, resulting in off-center firing pin strikes. Both conditions are probably due to wear on the hand, a critical part of the Colt (and any revolver) action.

Now, the real problem. Those Colts are long out of production and the factory will no longer service them and no longer has parts. And gunsmiths who know how to work on them are thin on the ground. You might try Cylinder and Slide, or do a search for Colt repairs. Or you can get a copy of Kuhnhausen's Colt books (from Brownells) and see what is involved.

One

 

[BSA1]

I agree it seems like a timing issue except;

The exterior of the gun is easily 98%.

The gun is very clean so whoever the previous owner was either didn't shoot it much or was careful about cleaning it.

The cylinder carries up and locks up fine when dry firing it regardless of how slow I cock it. With the S&W's that I have had being out of time showed up when dry firing. It seems more like a gremlin. I'll try disassembly and inspection just to be make sure it the gremlin isn't a foreign object or gunk.

The lack of knowledgable gunsmiths is a concern. C&S has done work for me in the past so I'll drop them a line also.

 

[rcmodel]

Do no more then take the cylinder crane out and carefully remove the side-plate.

Then flush throughly with WD-40 or other spray solvent.
Then blow it out and re-lube with light gun oil.

Removing the V-mainspring and further disassembly runs a certain risk if you have never done one before.

BTW: The Rebound Lever can easily get out of place with the side-plate off.
Beware when you go to put the side-plate back on.

rc

 

[BSA1]

What does the mainspring do with timing?

One last question.

What role does the mainspring play with the timing?

It appears the lower leaf of the mainspring of the mainspring presses on a "lever" (sorry I don't know the proper terminology) that helps operates the hand.

The reason I ask is the double action trigger pull is much lighter than on my Model 10 which had it's action repaired by S&W a couple of years ago.

Also the sideplate screws show very faint signs of having a screwdriver used on them indicating that they have at least been tighten once in the past.

Given the excellent overall condition of the gun this is causing me to suspect the gun has had a "action job" performed on it (and would explain why it was for sale at a such reasonable price).

p.s. I have sent a email to C&S.

 

[BBBBill]

The poor man's action job on those Colts often consisted of cocking the gun one time with a small diameter rod (think toothpick sized) inserted in the V of the mainspring. That de-arched the mainspring slightly. Not the right way at all, but lots of them were done that way and they functioned OK as long as the rod was small enough. Problem was that some decided if a little was good then more was better. So a 1/8" or larger punch got used instead. I've seen it first hand. Besides the reduced trigger pull, a de-arched spring can affect the proper function of some other parts if taken too far. There were a very few pros who could tune a mainspring by de-arching. Bill Laughridge (C&S) comes to mind. I think he bent his in a different place.

A lot of rambling to suggest that someone might have done that to you gun.

 

[BSA1]

No rambling at all. Like I said I don't know anything about Colt Double Actions.

Your information makes sense and helps me understand the workings of the gun.

Thank you.

 

[Old Fuff]

The poor man's action job on those Colts often consisted of cocking the gun one time with a small diameter rod (think toothpick sized) inserted in the V of the mainspring.

While this may, or may not work on mainsprings that were formed out of flat stock; don't try it on pre-World War Two revolvers that had forged springs with a tit at the bottom of the "V" that fit in a hole in the frame. The usual result is a broken spring, and replacements are not easy to find.

 

[BBBBill]

While this may, or may not work on mainsprings that were formed out of flat stock; don't try it on pre-World War Two revolvers that had forged springs with a tit at the bottom of the "V" that fit in a hole in the frame. The usual result is a broken spring, and replacements are not easy to find.

Agreed. I don't recommend it on any Colt, especially for someone not well versed in all of fine details and idiosyncrasies of these guns. I leave that to the experts that really know what they are doing. That was pretty much the intent of my post, although it may not have been as clear as it should have been.

 

[BSA1]

BBBBill,

Your post makes sense to me.

With S&W the hand operates separately from the mainspring whereas it looks like with the Colt the mainspring is doing two jobs. Well three if we include the trigger pull.

I am going to reload some rounds with CCI primers. If they fail to pop then that will support the theory of a altered mainspring as the Winchester and UMC primers popped the first time when they were hit in the center.

I've got a lot more research to do.

 

[Slamfire]

Off center primer hits don't help ignition. George Frost's book "Ammunition Making" has a neat section on the increased energy it takes for an offset firing pin hit to ignite a primer.

 

[dfariswheel]

Colt still repairs the Police Positive revolvers made since the 70's.

Also, for a faster turnaround and much better pricing then Cylinder & Slide, many Colt owners recommend Frank Glenn in Arizona.

http://www.glenncustom.com/

 

[BSA1]

Thanks for all of the advice.

COLT does not work on this gun as they do not have parts.

C&S is booked up for 14 months.

But Frank Glenn has time to look at it so off it goes.

 

[BSA1]

Colt Repair Update

Update.

I sent the gun to Frank Glenn for repair. He says;

"The condition of the revolver was called “throw by” where the bolt does not catch the cylinder notch."

"The occasional lock up of the trigger pull is caused by not letting the trigger go all the way forward, normally this only occurs when shooting DA as you mentioned. One way to keep this from happening is to have the shooter bump the front of the trigger guard with the trigger finger when releasing the trigger. Most S&W revolvers will do the same thing so it is not just the Colts."

Great fast service from Frank and I recommend him.