Gunsmithing Colts MkIII/V series, disassembly and reassembly.

[geronimojoe85]

From the Wikipedia article:

MK III
1969 - 1982 In the late 1960s, Colt began to be concerned with a decline in its market share because of price increases brought about by the high labor costs inherent in its manufacturing processes. In response, an entirely new product line of revolvers dubbed the MK III series debuted in 1969. Intended to be the first major advancement of Colt’s designs since the beginning of the 20th Century, the MK IIIs used a new ‘J’ frame and had no parts interchangeability with older models. The new revolvers were considered groundbreaking as they were the first modern revolver designs to employ a state of the art transfer-bar lockwork system. This lockwork was not only more sophisticated, but inherently safer due to its superiority to the older hammer-blocking designs; the revolver could fire only if the trigger was deliberately pulled completely to the rear. It also vastly improved on the earlier design in durability, and offered the advantage of employing sintered iron internal parts rather than expensive forged ones. The sintered parts also allowed for improved fabrication tolerances, and could be given a special heat treatment resulting in a harder more wear-resistant composition. Using these parts virtually eliminated hand fitting, significantly lowering labor costs associated with the assembly and manufacture of the MK III line.[2] The springs used in the Mark III internals were also an improvement. Unlike the older flat style, they were coiled and made entirely of corrosion-resistant stainless steel.[3]

The MK III series incorporated a number of models, several of which were updates of existing designs. Classic models included the venerable Colt Official Police chambered in .38 Special as the basic/entry-level offering, and the Trooper in .357 Magnum. New members of the line up included the Lawman, Metropolitan Police, and Border Patrol.[2][3]

Trooper
The .357 Trooper was the premier offering of the new product line, featuring a heavy barrel with a solid top rib as well as a shroud which protected the ejection rod. For the first time, the Trooper was offered with an eight inch barrel length, and as the top of the product line model it boasted a target-grade hammer, target stocks, and adjustable sights. The finish was upgraded to the lustrous Royal Blue or bright Nickel which had been typical on the .357 model, and an additional duller satin-nickel finish option, known as “Coltguard” was added. A new ammunition chambering option, the .22 Winchester Magnum Rimfire, also became available for the first time.[1][2][3]

Lawman
The Lawman was a .357 Magnum 'service grade' or 'police issue' version of the Trooper, equipped with smaller 'Magna Service' type stocks, a standard hammer, fixed sights, and barrel lengths of two inch and four inch only. The two inch barrel was an attribute unique to the Lawman, the only Lawman barrel equipped with shrouded ejector rod.[2][3]

To disassemble the MkIII

Remove the grips:


Remove the cylinder retaining screw:


Remove the detent and spring:


Slide the cylinder out the front of the frame:



Locate and remove the two small side plate screws:

With a small plastic hammer or wooden handle or other non-marring hammer like tool, gently tap the frame to release the side plate. DO NOT PRY UP THE SIDE PLATE!! The bottom will come up first:



Keeping tension on the cylinder latch will keep it in the frame as you remove it:

Locate and remove the transfer bar from the trigger:

Remove the hand from the trigger:


Cocking the hammer will compress the coiled mainspring and expose a small hole in the strut:


Place a paperclip into the hole and release the hammer, this will trap the mainspring on the strut:

Lift the mainspring assembly out of the frame:


Pulling the trigger to the rear will allow you to lift the hammer off of its stud in the frame:



At this point you can remove the double action sear from the hammer by sliding it out. Be careful to retain the plunger and spring:



Now you can remove the trigger by placing a punch or a screwdriver tip under the rebound spring to release tension and lifting the trigger off of its stud:


Next you can remove the rebound spring this is done by slowly sliding it up and off the stud using a punch or small screwdriver:


Remove the latch pin:



Remove the bolt by lifting the spring and sliding it out of the frame, keep your finger over the spring to keep it from flying into the dark reaches of your home and getting played with by your stupid cat only to find it after you've already ordered one from a sketchy website for colt parts that I'm pretty sure just steals your credit card information:


Drop the bolt out of the window in the frame and slide it off if the stud and out of the frame:

And there you have it, bare bones.

 

[geronimojoe85]

Reassembly begins with replacing the bolt and bolt spring:

With the bolt in place use a punch to control the spring and place it between the bolt and frame one arm of the spring at a time until it is in place:


Place the rebound spring on its respective stud. The long end of the spring should be against the solid side of the frame pointing towards the bolt stop:

Using a thin screwdriver blade bring the short end of the rebound spring over the lip small lip in the frame so it sits like this:

On the rear of the trigger you will see two small pins that can easily fall out.

Make sure they are properly installed with the larger ends facing toward your ugly mug.

By placing a small screwdriver under the rebound spring place the trigger on its stud and lift the rebound spring into the small end of that little pin.
Incorrect placement:

Correct placement (when placed correctly the trigger will have normal range and not bind):

Place the latch pin into the frame:

Place the double action sear spring and plunger into the hammer.


Compress the spring and plunger as you slide the DA sear into place. Be careful so the spring and plunger doesn't fly out into your big ugly goofy...

Look the hammer assembly looks like a bunny looking up.

Place the sear interface if the trigger between the double action and single action sears on the hammer as you slide the hammer onto its stud. Or put it between the bunny's front and rear paws. (That's adorable!).

Now place the mainspring assembly (the thing you put the paperclip in) into its slot in the grip portion of the frame.

And I just realized that the mainspring strut looks like we're going to be taking the bunny's temperature.
(I swear I haven't been drinking). Poor bunny.


Compress the spring and remove the paperclip. (Poor poor bunny.)

Now place the transfer bar onto the little pin here:

Place the hand on it's little pin, and compress the flat spring on the transfer bar. Like this:

Place the zigg-zaggy spring into the side plate:

Followed by the latch:

Compress the latch as you put on the side plate, notch in the top first and then straight down. Be careful to make sure the hand and transfer bar don't shift.
If you use a plastic hammer a light tap is all that it'll need. If you need more than that it's not on right. Again pretend the plate is made of porcelain, tap too hard and you're going to have a bad time:


Check the cylinder latch to make sure it works properly and doesn't bind, same for the trigger:

Now install the two side plate screws:

Place the cylinder in the front of the frame and latch it closed:

Replace the detent and spring:

Replace the screw:


Check for binding of the crane:

Replace the grips and you're golden.

 

[IndyGunworks]

Very well documented! And they say we don't need a gunsmithing forum while you are busy making the stickies for it.

 

[geronimojoe85]

Very well documented! And they say we don't need a gunsmithing forum while you are busy making the stickies for it.

All it takes is the mods to make it so.

 

[IndyGunworks]

And if you like your doctor you can keep them too.

 

[palerider0485]

thank you. thank you very much, good chance ill use that in the future.

 

[geronimojoe85]

Assembly is up.

 

[Indy_Guy_77]

Fantastic!

And I thought I was hot stuff for installing an Apex spring kit (https://apextactical.com/store/product-info.php?pid49.html) in my J-frame.

 

[BGDave]

Once again, thanks. If you ever want a challenge try a 1903 Colt. Mind bender. Edit to add; "M" model .32 acp or 380.

 

[M67]

Never had to take apart a MKIII, they just look funky without a V spring

 

[drillsgt]

Great job, and good photos.

 

[geronimojoe85]

Once again, thanks. If you ever want a challenge try a 1903 Colt. Mind bender. Edit to add; "M" model .32 acp or 380.

I might be able to make it happen.

 

[walt o]

Like someone said Colt hired RUBE GOLDBERG and a cast of his thousands to design the innards of colt revolvers by committee .
YOU can tell J.M.B had nothing to do with it

 

[jim.a]

Great job but most guy should never take a pistol apart

 

[chef larry]

I might be able to make it happen.

You may have a new job. Resident Gunsmith

 

[geronimojoe85]

I can get a model 1908 Colt .380, the more rare .380 cousin to the 1903.
Won't be till after the holidays though.
Until then I'm about to post one for the Beretta 92.