EARRRRR 'ya go........
1. SOME "J" frame firing pins are too hard. While few and far between, there is no practical way of telling. If the firing pin breaks, it means a trip back to Colt for a replacement. Under NO circumstances attempt this yourself, or allow anyone except the factory to do it. The firing pin retaining pin and the firing pin bushing must be pressed out with special support fixtures, and the bushing must be restaked with a special tool after the new pin is in place.
Best bet.....Use snap caps.
To remove the cylinder, remove the "screw" on the right front side of the frame. This is actually a cap, with a spring and stud underneath. Remove them and the cylinder and crane can be slid forward and off. For more disassemble see the book listed below.
The Trooper Mark III was designed to handle full Magnum ammo, although over pressure or really hot reloads will wear it prematurely. Stick to standard Magnum ammo and it will last about forever.
A brief history of the Mark III series.
By the late 60's Colt could no longer compete in the market with their older "I" frame revolvers like the Official Police and Trooper.
These old model guns required extensive hand fitting of parts, and the labor involved was pricing them out of the market.
In 1969 Colt developed the "J" frame series guns and discontinued all of the older "I" frame revolvers except for the Python.
The first gun in the series was the Trooper Mark III, based on the new "J" frame. Later guns were the Lawman, Metropolitan Police, and Official Police MK III, among others. Later guns based on the "J" frame were the Trooper Mark V, and the last in the series, the King Cobra.
The Trooper MK III guns were available in .357 Magnum, .22 Long Rifle, and .22 magnum.
Barrels lengths were 4", 6" and 8"
Finishes were Bright blue, bright nickel, and matt electroless nickel/"Colt Guard".
In the mid 80's the Trooper Mk III was replaced by the Trooper V, which had an improved double action trigger pull, a "short action"
and a reshaped butt completely covered by the grips.
Later the Trooper V was replaced by the almost identical King Cobra, which was basically the Trooper V made of stainless with a heavy lugged barrel.
The "J" frame was a first in the gun market in several respects.
It introduced the first modern revolver to use a transfer bar ignition system. This system was so simple and fool-proof, that every revolver designed since uses a variation of the Colt design.
Among others, Ruger, Dan Wesson, and Tauras use almost exact copies of the Colt system.
The "J" frame was also the first revolver made that was designed to use parts that required little or no hand fitting. Unlike the older Colt guns, the "J" parts are ALMOST drop in.
The down side of this is that unlike the older guns, a part that wears or becomes defective must be replaced. While older Colt revolver parts could be refitted, the "J" parts must be replaced, since no refitting is possible.
The "J" frame was also the first revolver to use "sintered steel" technology. This is simular to todays MIM technology.
In the sintered steel process, powdered metal is injected into a mould and heated to red heat. The metal melts and fills out the mould. Parts come out of the mould needing only fine fitting adjustments, and surface hardening.
Sintered parts include the hammer, trigger, bolt, and cylinder latch finger piece, among others.
The "J" frame parts are casehardened to provide a long wearing surface, and the hammers are color casehardened for appearance.
Most springs in the "J" frames are stainless steel coil springs.
The "J" frame action is one of the simplest revolvers ever designed, consisting of essentially a hammer, trigger, bolt, and transfer bar.
Jerry Kunhausen's book Gunsmithing the Colt Revolvers, Volume Two, the J, V, and AA guns, is recommended to any Trooper III owner. It gives complete details on disassembly and repair. It's money very well spent.
Kunhausen is of the opinion that these Colt revolvers may well be the strongest mid frame revolvers ever made, due to the forged and well heat-treated frames.
The Trooper Mark III is an absolutely first rate revolver unmatched by any of todays guns. The quality of the finish and fitting is amazing, considering the gun was to be Colt's "budget" line of revolvers. The blue job is closer to the Python than to the older Trooper type finishes.
I highly recommend the Trooper MK III in .22LR as a companion gun. The .22 is a very heavy revolver since it has the same frame and large cylinder only bored for the far smaller .22.
These large, heavy .22 caliber guns shoot more like rifles, and give lots of Trooper shooting at .22 caliber prices.
All in all, you've got a true classic gun that will far outlast you, given minimal care and a diet of reasonable ammo.
. I'll be up there in Greenville in a couple years though (Transfer to East Carolina).
...... still waiting for the bright day when I can get a Python though. Mmmmmm snakey goodness