Colt Python barrel on a Trooper Mark III
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dfariswheel
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Depends on the Python barrel.
The old style Python barrel threads are .5634-32 threads.
These old style threaded barrels are identified by having TWO pins in the front sight.
The new style Python threads are the same size as the Trooper Mark III/King Cobra.
These threads are .562-36 threads.
These new style threaded barrels are identified by having ONE front sight pin.
An old style Python barrel will NOT fit the Mark III without some major gunsmithing.
Fair warning: barrel changes, and particularly fitting different model barrels is NO "do-it-yourself" job.
It requires a major cash outlay for tooling, and you MUST know exactly what to do and how to do it.
Hint: screwing the barrel on is not the end of the job, it's just the beginning of a lot of high precision work.
Find a QUALIFIED pistolsmith who you KNOW has the right tools.
Hint: MOST local gunsmiths DO NOT have the right tools, and those who do have most of them almost never have the correct inserts for the frame wrench.
All too often they're tempted to use some "expedient" method of barrel removal and installation and ruin the frame.
Again, FAIR WARNING, this is how you ruin a nice gun.
The old style Python barrel threads are .5634-32 threads.
These old style threaded barrels are identified by having TWO pins in the front sight.
The new style Python threads are the same size as the Trooper Mark III/King Cobra.
These threads are .562-36 threads.
These new style threaded barrels are identified by having ONE front sight pin.
An old style Python barrel will NOT fit the Mark III without some major gunsmithing.
Fair warning: barrel changes, and particularly fitting different model barrels is NO "do-it-yourself" job.
It requires a major cash outlay for tooling, and you MUST know exactly what to do and how to do it.
Hint: screwing the barrel on is not the end of the job, it's just the beginning of a lot of high precision work.
Find a QUALIFIED pistolsmith who you KNOW has the right tools.
Hint: MOST local gunsmiths DO NOT have the right tools, and those who do have most of them almost never have the correct inserts for the frame wrench.
All too often they're tempted to use some "expedient" method of barrel removal and installation and ruin the frame.
Again, FAIR WARNING, this is how you ruin a nice gun.
Nutrz !
Well I think you have successfully de-suaded me from attempting this Frankengun. I got the Trooper for nothing, but it is too nice to butcher.
I guess I will look for a Trooper Mark V, or a King Cobra.
This is my first revolver, I think I see more in my future.
Well I think you have successfully de-suaded me from attempting this Frankengun. I got the Trooper for nothing, but it is too nice to butcher.
I guess I will look for a Trooper Mark V, or a King Cobra.
This is my first revolver, I think I see more in my future.
dfariswheel
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A wise decision.
The King Cobra is essentially what the re-barreled Mark III would have been.
Besides, you may be shocked at how accurate the Trooper Mark III is.
If you plan on dry-firing it much, use snap caps.
The firing pin "might" break, and this is a factory ONLY replacement part.
Another Fair Warning: Good revolvers are like potato chips and peanuts.
It's almost impossible to stop.
The King Cobra is essentially what the re-barreled Mark III would have been.
Besides, you may be shocked at how accurate the Trooper Mark III is.
If you plan on dry-firing it much, use snap caps.
The firing pin "might" break, and this is a factory ONLY replacement part.
Another Fair Warning: Good revolvers are like potato chips and peanuts.
It's almost impossible to stop.
JackOfAllTradesMasterAtNone
Member
Frame incerts and barrel vises and such....
Not to ask any of you to become the gunsmith college of THR, but could any of you toss up a couple photos and steps of the process of changing barrels or a cylinder or even 1911 sights?
This would not be meant that any of us would immitate the process, but more to educate us how things are done properly. This could be a huge plus when we talk to our local smith for a modification or repair.
There's been a lot of dicussion on trigger, hammer, sear, and safety fitting on 1911's and other guns. But I don't recall photos of the proper way to do it. Occasionally I'll see that someone has mastered the use of thier brand spanking new milling machine. But I don't think I've ever seen the step by step process of replacing a barrel, on a pistol or rifle. Cutting and re-welding a bolt handle comes to mind too.. I wish I took photos of glass bedding my rifle actions when I did them. I'd have been happy to share -even though I'm no GunSmith.
-Steve
Not to ask any of you to become the gunsmith college of THR, but could any of you toss up a couple photos and steps of the process of changing barrels or a cylinder or even 1911 sights?
This would not be meant that any of us would immitate the process, but more to educate us how things are done properly. This could be a huge plus when we talk to our local smith for a modification or repair.
There's been a lot of dicussion on trigger, hammer, sear, and safety fitting on 1911's and other guns. But I don't recall photos of the proper way to do it. Occasionally I'll see that someone has mastered the use of thier brand spanking new milling machine. But I don't think I've ever seen the step by step process of replacing a barrel, on a pistol or rifle. Cutting and re-welding a bolt handle comes to mind too.. I wish I took photos of glass bedding my rifle actions when I did them. I'd have been happy to share -even though I'm no GunSmith.
-Steve
dfariswheel
Member
- Joined
- Dec 26, 2002
- Messages
- 6,658
Here's a brief explanation of how to change a revolver barrel.
The old barrel is locked up in a barrel vise.
I used a dedicated bench vise into which I put a pair of custom made brand and model specific barrel inserts made of aluminum or a hard plastic.
As example, I had Colt Python inserts, Colt Trooper Mark III inserts, Colt shrouded barrel Detective Special inserts etc.
Since almost all of my barreling work was on newer revolvers that had ribs and lugs, this worked well.
For round barrels I used a standard rifle type vise with split brass inserts.
I had old model "skinny" barrel Detective Special rings, Colt old model Trooper rings, Official Police rings, etc.
With the barrel locked up, the frame wrench with brand and model specific plastic inserts is attached to the frame.
The wrench with the fitted inserts supports the frame and prevents either cracking or bending (tweaking) the frame.
I had inserts for the Colt medium frame guns, inserts for Colt "D" frame guns, etc.
The frame is "broken loose" and unscrewed from the barrel.
The frame threads are cleaned with solvent and brush, as are the threads on the new barrel.
The new barrel is test fit to determine how much needs to be cut off the barrel shoulder to allow the front sight to be at 12:00 o'clock top-dead-center when the barrel is properly torqued in place.
The amount needed to be cut is a judgment call based on experience.
The barrel is turned in the lathe to cut that amount off the shoulder.
Once the barrel is properly adjusted, the threads are coated with anti-seize compound.
The barrel is screwed in place and locked into the barrel vise, the frame wrench is attached to the frame and the frame is screwed on the barrel and torqued up until the front sight is aligned at 12:00.
Torque is critical.
Too much and and when the barrel is torqued until the front sight is aligned at 12:00, the bore may be compressed, leaving a tight spot in the barrel where the threads are.
Accuracy is poor.
Early non-pinned S&W revolvers had this problem from too much torque.
Too little torque and the barrel will unscrew from firing vibration, or can even turn FARTHER in.
With the barrel set, a special tool that works down the barrel's bore is used to set the barrel/cylinder gap.
This tool is a Tee handled rod passed down the bore with special cutter heads then attached to the rod.
A flat faced cutter is attached, and by pulling and turning the rod, the cutter will trim the rear of the barrel to set barrel/cylinder gap.
Care is taken to prevent scalloped or "wavy" cuts, and to insure the end is at 90 degrees to the bore.
With the barrel/cylinder gap set, another cutter head is attached, and this one is used to re-cut the forcing cone.
The forcing cone is a little understood barrel feature.
It's absolutely critical to accuracy, and the critical dimension is the OUTER diameter or "lip" of the cone.
If the outer edge of the cone is too big in diameter, accuracy will be poor.
Too small in diameter and accuracy is poor AND the revolver will spit lead.
Even used barrels MUST have the cone re-cut during installation.
The cutter heads are tapered cutters that cut a funnel shape in the rear of the barrel until the cone gages to the right outer diameter.
Various TAPERS may be used for special purposes. As example, a longer taper works best in a revolver intended for use mostly with lead bullets, a shorter taper for jacketed bullets.
The factory taper is a good compromise.
The cutter tool is used to cut the taper, and the progress is checked with a special plug gage that drops into the cone.
When the cone gages as in spec, a brass lapping cone head and fine valve grinding compound is used to lap the cone smooth of cutter marks.
The final step is shooting the gun for grouping.
As you can see, the barrel is NOT "just a piece of threaded pipe" that can be screwed on and off at will.
One sure-fire way of ruining a good revolver is to use the old gag of locking the barrel up in some rough wooden barrel blocks, shoving a hammer handle or piece of wood through the frame window and twisting the frame off.
This will either spring or bend the frame, or the frame will break through the frame's barrel threads, which are very thin on the bottom.
The old barrel is locked up in a barrel vise.
I used a dedicated bench vise into which I put a pair of custom made brand and model specific barrel inserts made of aluminum or a hard plastic.
As example, I had Colt Python inserts, Colt Trooper Mark III inserts, Colt shrouded barrel Detective Special inserts etc.
Since almost all of my barreling work was on newer revolvers that had ribs and lugs, this worked well.
For round barrels I used a standard rifle type vise with split brass inserts.
I had old model "skinny" barrel Detective Special rings, Colt old model Trooper rings, Official Police rings, etc.
With the barrel locked up, the frame wrench with brand and model specific plastic inserts is attached to the frame.
The wrench with the fitted inserts supports the frame and prevents either cracking or bending (tweaking) the frame.
I had inserts for the Colt medium frame guns, inserts for Colt "D" frame guns, etc.
The frame is "broken loose" and unscrewed from the barrel.
The frame threads are cleaned with solvent and brush, as are the threads on the new barrel.
The new barrel is test fit to determine how much needs to be cut off the barrel shoulder to allow the front sight to be at 12:00 o'clock top-dead-center when the barrel is properly torqued in place.
The amount needed to be cut is a judgment call based on experience.
The barrel is turned in the lathe to cut that amount off the shoulder.
Once the barrel is properly adjusted, the threads are coated with anti-seize compound.
The barrel is screwed in place and locked into the barrel vise, the frame wrench is attached to the frame and the frame is screwed on the barrel and torqued up until the front sight is aligned at 12:00.
Torque is critical.
Too much and and when the barrel is torqued until the front sight is aligned at 12:00, the bore may be compressed, leaving a tight spot in the barrel where the threads are.
Accuracy is poor.
Early non-pinned S&W revolvers had this problem from too much torque.
Too little torque and the barrel will unscrew from firing vibration, or can even turn FARTHER in.
With the barrel set, a special tool that works down the barrel's bore is used to set the barrel/cylinder gap.
This tool is a Tee handled rod passed down the bore with special cutter heads then attached to the rod.
A flat faced cutter is attached, and by pulling and turning the rod, the cutter will trim the rear of the barrel to set barrel/cylinder gap.
Care is taken to prevent scalloped or "wavy" cuts, and to insure the end is at 90 degrees to the bore.
With the barrel/cylinder gap set, another cutter head is attached, and this one is used to re-cut the forcing cone.
The forcing cone is a little understood barrel feature.
It's absolutely critical to accuracy, and the critical dimension is the OUTER diameter or "lip" of the cone.
If the outer edge of the cone is too big in diameter, accuracy will be poor.
Too small in diameter and accuracy is poor AND the revolver will spit lead.
Even used barrels MUST have the cone re-cut during installation.
The cutter heads are tapered cutters that cut a funnel shape in the rear of the barrel until the cone gages to the right outer diameter.
Various TAPERS may be used for special purposes. As example, a longer taper works best in a revolver intended for use mostly with lead bullets, a shorter taper for jacketed bullets.
The factory taper is a good compromise.
The cutter tool is used to cut the taper, and the progress is checked with a special plug gage that drops into the cone.
When the cone gages as in spec, a brass lapping cone head and fine valve grinding compound is used to lap the cone smooth of cutter marks.
The final step is shooting the gun for grouping.
As you can see, the barrel is NOT "just a piece of threaded pipe" that can be screwed on and off at will.
One sure-fire way of ruining a good revolver is to use the old gag of locking the barrel up in some rough wooden barrel blocks, shoving a hammer handle or piece of wood through the frame window and twisting the frame off.
This will either spring or bend the frame, or the frame will break through the frame's barrel threads, which are very thin on the bottom.
JackOfAllTradesMasterAtNone
Member
Very educational dfariswheel. I appreciate you taking the time to write this in detail. I am sure there are more details but that was very enlightening. Now, could someone explain this for a modern bolt action rifle? A lever gun? Maybe discuss muzzle crowning for various weapons and intended uses. Seems that every thing has a bit of machine crowning, but what's the difference between a target crown and a factory crown. If things have to be machined anyway, why don't manufactures of guns/barrels machine to a target crown at the end of the barrel? Don't they want their guns to be accurate? Rates of twist for a wad gun compared to a jacketed bullet gun?
Anything you gunsmiths want to write about is well appreciated by those of us just happy enough to be able to smooth out a trigger function, or change a set of sights.
-Steve
Anything you gunsmiths want to write about is well appreciated by those of us just happy enough to be able to smooth out a trigger function, or change a set of sights.
-Steve
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