Building a official police mkiii

[Shadyduk1979]

I am building a official police for my dad for Christmas. He refuses to allow me to buy him one, so when a friend gave me a bare frame I decided to build him one.

I know all mkiii parts interchange except for the python if my info is correct. I am down to only needing a hammer. I want to put a target hammer on and give the gun a trigger job. I found a parts kit from a MK iii trooper complete with barrel and cylinder and sights.

My question is, mostly out of curiosity is if I was to install a 357 cylinder and barrel, would the gun be safe to fire 357 magnum?

And the real question, I just want to be sure all the internal parts are in fact interchangeable. It would be far easier to build a working gun from a kit.

[Collects]

Can you use a Star 9mm slide on it?

lol

[Lawman67]

i
f it is a fixed sight frame, putting an adjustable sight Trooper barrel on it would not be a good idea. What model is the frame from?

[Shadyduk1979]

Frame is a Official Police MkIII I really just want to be sure all the guts are the same (I am pretty sure they are) in a Trooper MKiii.

The cylinder and barrel and sights are not going on the gun. I don't really think the sights will be able to be installed and be accurate and that and the barrel would have to be sent out which may not make it possible for this to be done for xmas, nor would i think it will work anyway, but i dont know for sure. I am more curious if it could be done.

[The Wingnut]

The MKIII Official Police frame is essentially the same as a Lawman, which is chambered in .357. I actually like the looks of the OP over the Lawman, but prefer the Lawman for its chambering. I think your primary concern would have to be the OP barrel, as it's thinner wall than the Trooper or Lawman. It might be able to handle the heavier loads of the .357 over .38, but I'll leave the answer to that question to someone with more experience on the subject.

So, short answer, YES, the parts are interchangeable, but you should use your head, and get a 'smith to at least assist in or do the work.

[smkummer]

Your gun should be safe in the .357 chambering. I had a Colt Lawman that I put a official police MK III barrel on and it work fine. The Official Police MKIII barrels are tapered and lighter but work just fine on a .357 chamber cylinder. Again it appears that all MKIII were designed around the .357 cartridge and pressure. I have a trooper MkIII in 38 that is identical to the .357 chambered trooper MKIII .357.Most likely it will be easier to find .357 cylinders than .38 special cylinders for the MkIII.

[dfariswheel]

All Mark III parts are the same except for some for the .22 versions.
Some of the same parts were also used in the Mark V, King Cobra, and even the Anaconda.

While the parts are all the same in the Mark III guns, not all parts will work.
The Mark III and later Colt's were built by pulling a part from a bin and test fitting it. If it didn't fit or operate properly, another part was pulled and tried until a fit was made.
The problem is that outside of Colt, no one HAS bins full of parts to work with. You have to order one part and if it doesn't fit, you have to send it back and order another, hoping it will fit.
It's this sending parts back that leads some gunsmiths to ignore the rules about not altering Mark III and later parts, and they start stoning or grinding parts to make them fit.
These parts are surface hardened and any filing, stoning, or even much polishing will break through the hard surface, exposing soft metal. The soft metal wears very quickly and you have an unsafe gun fast.

The second problem with assembling a DA revolver from parts or a "kit" is that cylinder and ejector assemblies usually don't fit properly.
Just because the cylinder will snap into the frame and seems to work is no sign it's really right.
Usually when fitting a cylinder, you start out by fitting a factory new ejector to the cylinder, then fit the assembly to the frame.
Problem is, there are no new ejectors available from anyone but Colt and they won't sell one unless they install it.

Another problem with revolver kits is that they're stripped police issue guns. The people selling the parts make up these kits with the parts stripped from the frame. If a part is damaged or looks bad, they just pull another part and toss it in. So, your kit may not all be from the same gun and that means assemblies aren't going to work out.

So, you "can" build a revolver from a kit, especially "machine fitted" guns like the Mark III where many parts are drop-in, but there's going to be fitting issues and issues with finding parts that fit correctly to replace the kit parts that don't fit.

As I recall, Colt built all Mark III "J" frames the same as far as heat treating. They decided it was easier and cheaper to build all frames the same instead of giving different heat treating to the .38 models and different treat to .357 models.
The barrel is not an issue since revolver barrels aren't under that much pressure. A modern .38 barrel will work for a .357.

When assembling a revolver from parts, pay very strict attention to head space, barrel/cylinder gap, and chamber/cylinder alignment.

[Shadyduk1979]

Thanks for all your help guys, I decided that this might be a nice way to show my dad the progress of the gun when he opens it on Christmas morning. I have been getting parts together as i can in the midst of all the other builds, work i have going on.

This is how the gun came to me, a frame and not much else. I have the original cylinder as well, its just not in the picture



I have a good amount of the parts, the rest are on the way. Just need a hand, extractor rod, and a .357 cylinder would be nice since the frame can handle it. Yes those are Sile grips, unless i see a original set soon for short money ill leave them.



I did a mockup of the gun with what i have so far. I borrowed parts from my trooper to do a function test, and found no issues thankfully.



Just for giggles, my aforementioned Trooper MKIII

[Collects]

Shady, thanks for showing us your fascinating project as you progress.

[Shadyduk1979]

Shady, thanks for showing us your fascinating project as you progress.

No problem, I was always a forum lurker. I usually just read and learned. After the kindness that A1A showed me in getting the hammer for this project, i decided its time to participate a bit more.