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Correction...I misread the question. My tongue was covering my eye tooth and I couldn't see what I was saying.
 

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I have a gunsmithing book by George Nonte that has a barrel thread illustration for different makes and models. I don't know if the Police Positive Special is different from just the Police Positive but the thread shown for the Police Positive is listed as .445" outside diameter with 32 threads per inch and the Diamondback is .553" outside diameter with 32 threads per inch.
Is this the info you wanted?
Mike
 

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Discussion Starter #4
I have a gunsmithing book by George Nonte that has a barrel thread illustration for different makes and models. I don't know if the Police Positive Special is different from just the Police Positive but the thread shown for the Police Positive is listed as .445" outside diameter with 32 threads per inch and the Diamondback is .553" outside diameter with 32 threads per inch.
Is this the info you wanted?
Mike
Yes that is the information I was looking for . Thanks Mr. Anderson
 

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Colt Police Positive revolver frames used the same threads for the later Diamondback, and for all Colt "D" frame revolvers like the Detective Special, Cobra, Agent, etc.
Since the threads were all the same, we sometimes see a Detective Special barrel installed on a Cobra, or a Detective Special barrel installed on a Police Positive Special, either as an expedient barrel to replace a damaged barrel or because someone wanted a short barrel on a longer barreled PPS.

While a Diamondback barrel might fit onto a Police Positive Special frame, they will not mate up properly.

Once in a while you'll see a Python barrel screwed on a Colt original Trooper frame. The front of the frame does not match up with the Python barrel top rib, and that leaves a really ugly gap between the rib and frame.

The same problem will happen with a Diamondback-PPS installation.
In the late 60's a number of custom gunsmiths installed Python barrels on original Trooper frames, but they had to Heli-Arc weld up the top-front of the Trooper frame so the frame would mate with the Python barrel rib.

Notice how the Police Positive and other Colt "D" frame revolvers like all Colt fixed sight models have a significant bevel on the top-front of the frame.
Revolvers like the Diamondback have a flat topped frame so it will match up with the barrel top rib.
If you install a ribbed barrel on a fixed sight frame there will be a super obvious and ugly gap between the top rib and the top-front of the frame.
 

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Discussion Starter #6
Thank you dfariswheel . The reason I ask is that a few years back i bought a Police Positive Special because it had a set of Colt original Diamondback Grips on it . The PPS barrel is in rough shape and was thinking what I should do with it . Now I have a follow up question . The PPS that I have has a 4 inch barrel on it . Could I put a Detective Special barrel on it ? Would the ejector rod be too long ?
 

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If you put a DS pre-1972 barrel without the ejector rod shroud you shouldn't have an issue. I don't know if that holds with a later DS barrel.
 

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A Detective Special barrel will fit just fine on a PPS frame.
As above it's not unusual to see a PPS with a Detective Special or Cobra barrel on a Police Positive Special frame.
Sometimes someone just wanted a Detective Special type revolver and instead of buying one, they just converted a PPS to a short DS barrel.

Whether the ejector rod and rod head would be too long depends on the age of the PPS.
During various eras Colt used longer or shorter rods on the PPS and longer or shorter rod heads.
To check what will work, just measure your current barreled PPS from the front of the cylinder 2 inches and see where the end of the rod and head are.
If the rod and head are longer then 2 inches, you'd need a shorter rod and probably head.

In any case, if you have a PPS made before the change to the new style Colt ejector rods, ejector rods are still fairly available.
To find out what you have, put three EMPTY cases in the chambers and use padded pliers to grip the ejector rod HEAD and try to unscrew it. If the entire rod starts to unscrew it's a new style.
If the rod head unscrews it's an old style.

The change from the old to the new happened sometime in the 1970's? so if your PPS is older it will be the old style.

I assume you know that changing revolver barrels is FAR more complicated then many people think.
It requires significant tooling, and "expedient" tools like shoving a piece of wood through the frame window and twisting the frame off will almost always bend or crack the frame.

Replacing a barrel will require a lathe or bench trimming tool to trim the barrel shoulder so the front sight will line up, the rear of the barrel will need trimming with a precision cutter tool to set barrel-cylinder gap, and the critical forcing cone will need to be re-cut, gauged, and honed.

A smart move would be to have a barrel installed by Frank Glenn or Spartan..... both of whom are forum members.
 

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Discussion Starter #10
THANKS AGAIN DFARISWHEEL . I think I will just keep it as is . Unbelievably it shoots very accurately with the pitted barrel . I am the kind of guy that doesn't look for problems . Once again COLT FORUM has saved me from STRESS AND HIGH BLOOD PRESSURE . I am going to let a TRUCK GUN BE A TRUCK GUN .

THANKS AGAIN EVERYONE
 

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THANKS AGAIN DFARISWHEEL . I think I will just keep it as is . Unbelievably it shoots very accurately with the pitted barrel . I am the kind of guy that doesn't look for problems . Once again COLT FORUM has saved me from STRESS AND HIGH BLOOD PRESSURE . I am going to let a TRUCK GUN BE A TRUCK GUN .

THANKS AGAIN EVERYONE
i know you’ve made up your mind but it can be done. I purchased an 8 inch Python at a good price that had a barrel more pitted than I could stomach since the rest off the gun was perfect. I found a NOS barrel on eBay at a reasonable price and had Spartan Arms install it. I know I was tempting fate because the pitted barrel shot awesome. However, I didn’t need to worry, Spartan did a great job and the new barrel shoots just as awesome. Cost was very reasonable. Python looks great and I have the original barrel if I ever decide to sell it.

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