View Full Version : Colt Python with throw-by on one chamber

June 1, 2012, 04:39 PM
I own a Colt Python made in 1981 and I’m sorry if my question has been answered. I did a search and found many posts on Pythons, but not exactly one that describes my problem.

After following Dfariswheel's checklist for Pythons I realize that I have a case of throw-by on one of the chambers when firing in DA. This happens whether I pull a slow or fast DA. It dos not happen in SA. The bolt drops where its suppose to drop on all chambers, but on one of the chambers it lands in the middle of the ramp like the others, but then jump past the notch.

The hand is obviously the same so I believe the problem is located to the cylinder. I can see some variations to the different spokes on the crane.

After about 100 dry shots, on snaps, I get a fine dust of brass on the back of the cylinder, and the snap caps show fine marks along the edge of the rim. I do not know if this is related to my other problem.

In addition I live in Norway so shipping the gun to Hartford is unfortunately no longer an option.

If anyone have an idea for a diagnosis, and perhaps a cure I’d really appreciate it.

June 1, 2012, 07:53 PM
Due to the complex Colt action, unless we can see it, it's tough to offer much help.

This could be caused by a deformed lug on the ejector or it could be a burred or narrow locking notch on the cylinder.

My first move would be to order a copy of the Jerry Kuhnhausen shop manual on the Colt revolvers.
Volume One covers the Python and all the older style Colt's.

This shop manual was written as a training manual for new gunsmiths.
It shows Colt factory repair methods and is the best source of Colt revolver information there is.
Using the manual should help you diagnose the problem and the repair.
The main use of the manual is to properly diagnose the EXACT problem and eliminate attempting to repair something that isn't the problem and causing even more trouble.

This manual is money VERY well spent for the Colt owner.
If you don't feel up to attempting repairs, you could loan the manual to a local gunsmith.


As for the brass dust and scratches on snap caps.
This could just be the soft caps rubbing on the harder steel frame, or there could be a burr on the breech face of the frame.
Examine the face of the frame, especially around the firing pin hole for any burrs.
I would suspect it's just the snap caps.

June 2, 2012, 01:19 AM
I thought all gurus were clairvoyant :)

I'm partial to the idea that the problem is a deformed lug. Everyone of them seems to be different. I am unsure where the hand is when the hammer falls.

Anyway point taken and book ordered. Thank you for the reply.

June 2, 2012, 07:27 PM
Some advice on the Kuhnhausen shop manual:

The manual was written as a training AID, to be used in conjunction with the instructors direction, and he figured the students would be smart enough to really study the manual.

For these reasons, he doesn't hit you between the eyes with important data. You have to actually study the manual closely and catch the critical information yourself.
Many people give the manual a fast read and complain that their specific problem isn't clearly addressed.
It is, but it's not obvious.

Remember that the old Colt action is one in which every part has at least two totally separate functions, and the entire action is interrelated. Other brands of guns are mostly composed of parts that perform one function and that function isn't really related to any other.
Your specific problem could be somewhere totally unexpected or even unsuspected.

Be very aware at all times that if you change something "here", something that seems to not be related happens "over there".
And last, remember that one of the every first rules of gunsmithing is to be 100% certain of the actual problem and the fix before altering anything.
It's common for Colt's to be taken to a non-Colt qualified gunsmith only to have it come back with other problems because the 'smith altered something without really understanding what he was doing.

The old Colt action can be very frustrating to work on, and frustration can easily lead to altering something in the blind hope that that will fix the problem. When it doesn't, you've just started digging a hole that can ruin a good gun.

James K
June 4, 2012, 09:06 PM
I will vote for a cylinder notch that is a bit narrow or that has been battered a bit and is too narrow to accept the bolt.

I usually corrected that using a pattern makers file, but I never had to do it with a Python. It is not a hard job or difficult, but VERY prone to having the file slip and scatch the cylinder, not a nice thing with a Python. It helps to cover all but the tiny area you are working on with a couple of layers of Scotch tape.


Sharpsdressed Man
June 5, 2012, 05:59 PM
Good luck. I have abandoned Colt revolvers for any kind of general use. Every one that I have had developed some kind of wear or timing/alignment problem requiring being sent in for service. They are beautifully crafted, but do not stand up to prolonged use, from what I can tell.

4V50 Gary
June 7, 2012, 07:15 PM
Also Check the star extractor. Is the one where the cylinder is throwing misshapen or dirty?

June 8, 2012, 08:50 AM
Take a good picture of the ratchet/star extractor/lug (the back of the cylinder), and post it here. If all the chambers align correctly when dry-firing except one (the same one each time), the problem almost has to be a lug problem. A picture should show if that is the problem.
File on nothing, make no attempt at repair until the problem has been correctly indentified.

Harry Bonar
June 9, 2012, 06:55 AM
This is common in Colt revolvers! And lots of crane and timing issues.
Harry B.

June 9, 2012, 10:43 AM
This is common in Colt revolvers! And lots of crane and timing issues.
Harry B. If that is true, and I have no reason to doubt, that knowledge does not help the poster with his problem. He most likely posted his problem because he wanted some guidance on what was likely to be the cause and how to fix it. With your post and a time machine he could go back in time and just not buy it. I am sure that he would rather you give him the benefit of your knowledge and experience if you would only share it with him, and us, of course.

Harry Bonar
June 10, 2012, 07:20 PM
There is no fix other than to send it back to Colt.
Harry B.

June 10, 2012, 08:31 PM
Or, if it is one of the lugs on the ratchet as it sounds like, one may purchase a new ratchet here:
And, have a gunsmith fit it.

James K
June 13, 2012, 03:57 PM
I don't claim to the be world's greatest eggspurt on Colts and I agree with Dafariswheel that working on them can be interesting, to say the least,
but I really don't see how the ratchet can cause throwby. The way the Colt is designed, the cylinder will always throw by unless the bolt stops it, as the second step of the hand is set up to maintain pressure on the ratchet even after the cylinder stops. That can be changed, but then the gun won't have that "bank vault" lockup that Colt was famous for.

So if a Colt throws by, the bolt (cylinder stop) is either not coming up, is not coming up fast enough, or is not fitting into the cylinder notch. The second condition is sometimes seen when firing very fast, but the strong spring in the bolt (unless weakened) will usually ensure that the bolt snaps up with authority. When only one notch is involved, it is probable that that notch is too narrow or is being blocked, for example by metal displaced by the bolt itself or from some other damage. If the bolt fits properly into the other notches, then the bolt should not be narrowed; the better approach is to VERY CAREFULLY widen that one notch.

This does not mean to get out the Dremel tool, the big grinder and the double bit axe. Working on those Colts (especially a Python) is not for the ham-handed or the amateur.

So, I will second Harry Bonar - send it back to Colt.

June 13, 2012, 06:15 PM
If a ratchet lug is deformed or otherwise defective, it could cause throw-by by allowing the hand to push the cylinder too far.
This would be the same as an out of time action allowing the bolt to drop too close to the cylinder locking notch.

If the bolt is dropping too close to the notch, you can get throw-by.
I'd suspect the lug would have to be really bad for this to happen.

James K
June 13, 2012, 08:03 PM
The bolt would have to be dropping very late, in fact, after the notch has passed.

The Colt is set up so the hand exerts force on the ratchet until past the cylinder notch, in other words, a Colt will ALWAYS throw by unless the bolt stops the cylinder. (Try it with a piece of cardboard blocking the bolt or without the bolt in place and see.) That is normal. What is not normal is for the bolt not to stop the cylinder; as I said, either the bolt is not coming up properly, or the cylinder notch is partially blocked. A deformed or worn bolt could also be the cause, but then it should fail on all chambers, not just one.


June 14, 2012, 07:03 AM
I have a case of throw-by on one of the chambers when firing in DA. This is central to the discussion. The fact that it is exclusively a problem on one chamber and the same one each time, would logically rule-out everything but the lug area of that chamber. A close-up picture of that area would be great.

James K
June 14, 2012, 06:44 PM
Or that ONE cylinder notch.


June 15, 2012, 08:41 AM
Or that ONE cylinder notch. Yes of course. However, if there was a burr on the notch edges, that should be readily apparent. And, "...It dos not happen in SA..."

Despite what has been posted, should not require a trip to Colt; should not be cause of, "the sky is falling", or other hysteria.

I sure do wish he would post pictures.