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Discussion Starter #1 (Edited)
I recently purchased a NIB (never fired) 4 inch Colt Python through GB. Yesterday I fired it for the first time. I would like to keep this gun f-o-r-e-v-e-r, and expect to fire it often and maintain it well.

So after a mix of 25 - 357 FMJ Magnums and 40 - 38 Special FMJ rounds I had a miss fire. So I called it a night, and brought some spent cartridges and the miss fire home for comparison. I have attached a photo here.

Tonight I returned to the range and fired about 6 cylinders of 38 target rounds and got 6 more miss fires for my trouble.

I cannot understand how this could happen with a NIB Python, and need some informed diagnosis on what is wrong.

Here are a couple of images:

4-17-12Missfire.jpg ondesk.jpg
 

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Probably a weak hammer V-spring. I had the same thing happen with my 1960 Colt 357, sort of the same revolver. I have never fired it much, and it started misfiring first in DA, then later in SA. 2 cures - get a replacement spring or bend the existing spring. I did the latter, and it is still working OK after about three years. Simple job to do either.
 

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Looks like an off-center strike.
This is usually a symptom of "Throw-by". That's a condition where the gun fails to lock up and the cylinder rotates past the locking position. In this condition, the cylinder is rotating too far.
This is dangerous since the gun can fire in an unlocked condition. DO NOT continue shooting it until you've diagnosed the problem, or sent it in to Colt for correction.

There are a number of reasons for throw-by to happen.
The most common is the gun is out of time and the cylinder locking bolt is dropping too late. With the bolt dropping too late, it doesn't have enough time to intercept and lock into the notch on the cylinder.
The cause of this out of time condition could be simply an action dry of lubricant, or the gun needs adjustment.

It's the nature of revolvers, especially the old Colt action models for the shooter to himself cause throw-by by a hesitant or jerky trigger pull or by improper attempts to "stage" the action.
A hesitant or jerky pull on the trigger or attempting to give the trigger a jerk to get the cylinder to rotate to lock (staging the trigger) can cause the cylinder to be rotated past lock up.

First, check the timing of your Python. Unlike other brands of revolvers, the old Colt actions timing is absolutely critical. Everything MUST happen in the right order, and at exactly the right moment.

If timing seems to be proper, try lubricating the action.
If timing is off, or you can't determine the problem, send the gun in to Colt for repairs. Some Pythons are still covered under the warranty. DO NOT take it to a local gunsmith.

Here's my instructions on checking timing:
BOLT RETRACTION AND "SNAP BACK".
Open the cylinder and look at the small "lug" in the bottom of the cylinder window. This is the cylinder locking bolt.
Cock the hammer, and watch as the bolt retracts into the frame and pops back out.
The bolt MUST begin to retract THE INSTANT the hammer begins to move.
There MUST be NO (ZERO) hammer movement possible before the bolt starts to retract.
The bolt should retract smoothly with no hesitation until it's fully retracted,then it must pop back out with a clean "snap".
There should be no hesitation, and no amount of "creeping" back out.

CYLINDER UNLOCKING.
Close the cylinder.
Use your left thumb or fore finger to again cock the hammer, closely watching the cylinder bolt as you SLOWLY cock the hammer.
As the hammer comes back, the bolt will retract away from the cylinder.
The bolt must retract far enough to unlock the cylinder BEFORE the cylinder begins to rotate.
If the bolt is still slightly engaged with the cylinder lock notch, the cylinder will be attempting to turn while still partially locked.
This produces a "catch" or "hard spot" in the trigger pull and will damage both the bolt and the cylinder lock notches.
This often appears as metal "pulled out" of the lock notches, with rounded off and burred notches.

BOLT DROP TIMING.
Continue to cock the hammer, LIGHTLY laying your right index finger on the cylinder just enough to prevent "free wheeling".
Watch for the bolt to drop back onto the cylinder. WHERE the bolt drops is CRITICAL.
The bolt MUST drop onto the leade or ramp in front of the actual cylinder notch.
If the bolt drops too soon, (in front of the notch ramp), it will mar the finish of the cylinder.
The bolt should drop into “about” the middle of the ramp.
If the bolt drops late, (farther toward the actual locking notch) the revolver may display "cylinder throw-by".
In this condition, during double action shooting the cylinder may rotate PAST the locking notch, and fire in an unlocked condition.
It's the nature of the Colt action, that a hesitant or jerky trigger pull by the user can induce throw-by in even a properly tuned Colt.
The Colt trigger should be pulled with a smooth, even pull, with no sudden jerks at the beginning.

CYLINDER LOCKUP.
Continue to pull the hammer back and both watch and listen for the bolt to drop into the cylinder lock notch.
The bolt must drop into the actual lock notch before or just as the hammer reaches full cock.

The most common Colt mis-time situation is the hammer cocks before the bolt drops into the lock notch. (Hammer is cocked, but cylinder isn't locked).
In this condition, with the hammer fully cocked, you can push the cylinder slightly, and you will hear the "CLICK" as the bolt drops into lock.
In my experience, most Colt's leave the factory with the bolt dropping a little late into the leade, but usually wear in to correct timing.
If the bolt drops onto the cylinder early, no real problem, but there will be extra finish wear.
If the bolt drops late (closer to the lock notch) the cylinder may "throw by" or rotate TOO far in double action and this can cause off-center primer hits and firing while unlocked.

Each of these checks should be done on EACH chamber. All of these checks are better done individually. In other words, do the bolt retraction check on all six chambers, then do the bolt drop test, and so on.

A properly tuned Colt will:
Have a smoothly functioning bolt with no sticky or hesitant movement.

Unlock before the cylinder begins to turn.

The bolt will drop onto the middle of the ramp.

The bolt will drop into the lock notch just before or as the hammer reaches full cock.

Have a smooth trigger pull, which does "stack" or get heavier as the trigger is pulled.
 

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With the aftermarket stocks, it is likely that this Python is not really "unfired." That said, the gun should not misfire. A weak mainspring (usually caused by someone sticking a screwdriver deed in the "V" of the spring and pulling the trigger to lighten the double-action pull and going too far, which can be fixed as DWait suggests) is probably the cause, but DFW has identified other possible causes that should be considered.
 

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I had a NIB Python and I experienced similiar when I first shot it. I replaced the spring and it never reoccured. Numrich has them.
 

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I have the same problem in double action only. One cylinder does not fire every time. In single action mode everything works fine. I can't seem to find anyone that can tell me what is wrong with it so I am going to send it to colt and have them give it a once over.
 

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Your first photo clearly shows peening of the case and not the prime. Do NOT overlook A1A's post. He has given a thorough procedure for determining if the gun is out of time or is shooter error. After you've decided do not hesitate to return the gun to Colt's if it is out of time; the gun is unsafe to shoot. If that is the case, it may be a good idea to call them and go over their policy of returns.
 

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I have the same problem in double action only. One cylinder does not fire every time. In single action mode everything works fine. I can't seem to find anyone that can tell me what is wrong with it so I am going to send it to colt and have them give it a once over.
In DA, the hammer does not cock as far as SA. Therefore the fall is shorter and provides slightly less force to ignite the primer(s). This can show up a marginal spring. As for it being one cylinder, if it is always the same one and your strike is obviously off center, there can be other minor issues with the ratchet, for example, that can contribute to that. I'm not sure why you flatly say that no one can tell you what is wrong with it. First, it is indeed difficult to provide a 100% guaranteed diagnosis based on description. It requires detailed symptom description, feedback from checking and trying things and sometimes hands on. If you have not tried replacing or re-arching the spring and are unwilling or unable to do so, then indeed you have little choice but to send it somewhere, preferably Colt. :)

 

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From the photo, it appears to me your firing pin strike indentation is OK. Try bending the hammer V-spring a little first, as shown, as a weak spring is the most likely cause. Back in the early days of DA revolvers, it was not uncommon for misfires to occur due to the lighter DA strike. In fact, some ammunition manufacturers went to a slightly more sensitive primer (by making the cup metal a little thinner) to cure this problem. Of course, that should not be the situation today.
 

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All the primer hits look pretty well centered and deep enough,except for the one that misfired .It obviously hit way off on the edge of the primer or missed it completetly. This verifies dfraisswheel assesment that it threw by. Were you shooting single or double action? was the misfire in da? Or did you cock the hammer back in sa real hard on that one?
On the other misfires that there are no pics of, were they in da or sa?
I would check the primer hits on all the ones that misfired- if they all look like the one you showed, then obvioously its is not the sprng that is the problem -it is throwing by thats the problem. If however the hits are lighter in da then the spring might e the problem.
I would also put snapcaps in it and dry fire it alot in both sa and da to determine when and why it misfires and check the bolt each time it does misfire. if the bolt is not engaged in the notch ,you will know of course what the problem is.

I had a DS that had an intermittent problem like this. every once\in awhile it would throwby but it was very intermittent. The spring was not the problem as sa and da hits were plenty hard enough. I tweeked the bolt tip and after many trials i finally fixedthe problem. I then dry fired it over and over in sa and da to check and recheck and it never threw by again(at least not in the last couple years).
Your problem may not be the same but I would definitely test it to see ifyou can narrowdown the cause.
Good luck
 

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A1A, Thank you for the reply and diagrams. I have brought this problem up to a few lgs in my area and no one had a clue what may cause this problem. I did try and also ask here on the fourm a while back but couldn't find anyone that new what it may be at that time. I am not comfortable with doing the work myself so I will probably send it to Colt and see what they can do.

Does anyone know of a qualified gunsmith near the Sarasota, Fl area that may be able to do this work?
In DA, the hammer does not cock as far as SA. Therefore the fall is shorter and provides slightly less force to ignite the primer(s). This can show up a marginal spring. As for it being one cylinder, if it is always the same one and your strike is obviously off center, there can be other minor issues with the ratchet, for example, that can contribute to that. I'm not sure why you flatly say that no one can tell you what is wrong with it. First, it is indeed difficult to provide a 100% guaranteed diagnosis based on description. It requires detailed symptom description, feedback from checking and trying things and sometimes hands on. If you have not tried replacing or re-arching the spring and are unwilling or unable to do so, then indeed you have little choice but to send it somewhere, preferably Colt. :)

 

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So are Colt DA's not to be fired double action slowly/hesitantly?
I do this a lot. You just about have to in order to hit something smaller than a tv.
Smiths don't have this problem.
 

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So are Colt DA's not to be fired double action slowly/hesitantly?
To the contrary, one would better caution about jerking the trigger rapidly as overly abusive. Doing so can actually promote throw by even in a properly timed revolver. The issue with slow cocking in either SA or DA is that it can show up a slightly worn hand because the cylinder may not rotate to lock before the hammer is fully cocked in SA or falls in DA. Cycling the action slightly faster causes the cylinder momentum to carry it to lock. While many consider this to be normal and correct, it is not. In a correctly timed revolver, the cylinder should should lock before full cock in SA and just before the hammer falls in DA no matter how slowly you cycle the action. :)
 

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Discussion Starter #17
Sent to Colt's today, and asked them to fix it. I also asked them to replace all the springs they have available.
 

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Discussion Starter #18
The misfires occur during both SA & DA, and they all look exactly like the one in the image. I don't think I jerk the trigger in DA. I am hitting what I am aiming at - when it fires!

I included the unfired rounds in the box I sent to Colt, and also requested a "Python Custom Tune" while it is there. As long as I am spending $$ to get it working properly, I thought hey, why not empty my wallet.

Cheers
 

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This is such an informative post it really should be a sticky. tons of valuable info here and thanks to all members who supplied it you are a godsend!
 

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The misfires occur during both SA & DA, and they all look exactly like the one in the image. I don't think I jerk the trigger in DA. I am hitting what I am aiming at - when it fires!

I included the unfired rounds in the box I sent to Colt, and also requested a "Python Custom Tune" while it is there. As long as I am spending $$ to get it working properly, I thought hey, why not empty my wallet.

Cheers
Just so you know what a regulated age we live in, live ammo can only be sent via ground services. Handguns require the next day air. Technically, you can't send them together. :cool:
 
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