CHECKING THE TIMING OF THE OLD STYLE COLT REVOLVER
Revolver "timing" is simply the process of the unlocking, advancing the cylinder to the next chamber, and re-locking it.
This must happen in the proper sequence and at the proper moment.
In most revolvers this process is far less critical than the old style Colt revolver action.
In the old style Colt's, correct timing is absolutely critical and timing must be exact.
These instructions cover all the older model Colt's like the Detective Special, Cobra, Diamondback, Official Police, Officer's Models, original Trooper, and Python.
BOLT RETRACTION AND "SNAP BACK".
Open the cylinder and look at the small "lug" in the bottom of the cylinder window. This is the cylinder locking bolt.
Cock the hammer, and watch as the bolt retracts into the frame and pops back out.
The bolt MUST begin to retract THE INSTANT the hammer begins to move.
There MUST be NO (ZERO) hammer movement possible before the bolt starts to retract.
The bolt should retract smoothly with no hesitation until it's fully retracted, then it must pop back out with a clean "snap".
There should be no hesitation, and no amount of "creeping" back out.
CYLINDER UNLOCKING.
Close the cylinder.
Use your left thumb or fore finger to again cock the hammer, closely watching the cylinder bolt as you SLOWLY cock the hammer.
As the hammer comes back, the bolt will retract away from the cylinder.
The bolt must retract far enough to unlock the cylinder BEFORE the cylinder begins to rotate.
If the bolt is still slightly engaged with the cylinder lock notch, the cylinder will be attempting to turn while still partially locked.
This produces a "catch" or "hard spot" in the trigger pull and will damage both the bolt and the cylinder lock notches.
This often appears as metal "pulled out" of the lock notches, with rounded off and burred notches.
BOLT DROP TIMING.
Continue to cock the hammer, LIGHTLY laying your right index finger on the cylinder just enough to prevent "free wheeling".
Watch for the bolt to drop back onto the cylinder. WHERE the bolt drops is CRITICAL.
The bolt MUST drop onto the leade or ramp in front of the actual cylinder notch.
If the bolt drops too soon, (in front of the notch ramp), it will mar the finish of the cylinder.
The bolt should drop into “about” the middle of the ramp.
If the bolt drops late, (farther toward the actual locking notch) the revolver may display "cylinder throw-by".
In this condition, during double action shooting the cylinder may rotate PAST the locking notch, and fire in an unlocked condition.
It's the nature of the Colt action, that a hesitant or jerky trigger pull by the user can induce throw-by in even a properly tuned Colt.
The Colt trigger should be pulled with a smooth, even pull, with no sudden jerks at the beginning.
CYLINDER BOLT LOCKING.
Continue to pull the hammer back and both watch and listen for the bolt to drop into the cylinder lock notch.
The bolt must drop into the actual lock notch before or just as the hammer reaches full cock.
The most common Colt mis-time situation is the hammer cocks before the bolt drops into the lock notch. (Hammer is cocked, but cylinder isn't locked).
In this condition, with the hammer fully cocked, you can push the cylinder slightly, and you will hear the "CLICK" as the bolt drops into lock.
In my experience, most Colt's leave the factory with the bolt dropping a little late into the leade, but usually wear in to correct timing.
If the bolt drops onto the cylinder early, no real problem, but there will be extra finish wear.
If the bolt drops late (closer to the lock notch) the cylinder may "throw by" or rotate TOO far in double action and this can cause off-center primer hits and firing while unlocked.
CYLINDER LOCK UP.
The older style Colt's had what was known as the Colt "Bank Vault" lock up.
When the trigger is pulled and held back there should be no rotational movement of the cylinder. In these Colt's the hand forces the cylinder chamber into into perfect alignment with the bore and locks it tightly there.
Each of these checks should be done on EACH chamber. All of these checks are better done individually. In other words, do the bolt retraction check on all six chambers, then do the bolt drop test, and so on.
A properly timed old style Colt will:
Have a smoothly functioning bolt with no sticky or hesitant movement.
There will be zero movement of the hammer without the bolt starting to retract.
Unlock before the cylinder begins to turn.
The bolt will drop onto the middle of the ramp.
The bolt will drop into the lock notch just before or as the hammer reaches full cock.
Have a smooth trigger pull, which does "stack" or get heavier as the trigger is pulled.
CHECKING THE TIMING OF THE NEW STYLE COLT REVOLVER
Here's how to check timing on the Mark III and later Colt action:
This covers post-1969 Colt DA revolvers, to include:
The Trooper Mark III, Lawman, Metropolitan Police, Official Police Mark III, Trooper Mark V, Lawman Mark V, Peacekeeper, and King Cobra.
This "probably" covers the Anaconda and the new small frame revolvers based on the "SF" frame, like the SF-VI, the DS-II, and the Magnum Carry since these are all based on the King Cobra.
BOLT RETRACTION AND DROP.
In these guns, the bolt retraction and drop is judged by TRIGGER movement.
The bolt should begin to retract within 1/6 to 1/4 of the triggers total movement and drop after about 2/3 of it's total arc.
This is NOT 1/6 to 1/4 INCHES, it's total trigger movement.
What counts is that the functions occur correctly even if trigger movement is slightly off.
BOLT ACTION.
Open the cylinder and look at the small "lug" in the lower frame window.
This is the cylinder locking bolt.
Slowly cock the hammer and watch the bolt as it retracts.
When the bolt begins to retract, it should move smoothly in, then pop back out with a clean "SNAP".
There should be little or no mushy or hesitant movement.
BOLT DROP.
Close the cylinder and slowly cock the hammer.
Watch the TRIGGER AND the BOLT.
The trigger should move between 1/6 and 1/4 of its arc before the bolt begins to retract.
What's critical here is that the bolt MUST be retracted enough to be completely free of the cylinder locking notch BEFORE the cylinder begins to rotate.
BOLT DROP.
Again, the standard for bolt drop is based on TRIGGER movement.
The Bolt should drop after about 2/3 of the trigger's total travel.
What's critical here is, the bolt should remain retracted away from the cylinder while the cylinder rotates and then drop back onto the cylinder before the trigger gets too close to the end of it's movement, the sooner the better.
CYLINDER LOCKING.
Before the hammer is cocked, the bolt MUST drop into the cylinder locking notch, locking the cylinder.
Unlike the older Colt actions, there's a wide range of adjustment allowed, and the bolt DOES NOT drop into the leade to the cylinder locking notch.
Since the bolt is designed to ride the cylinder for most of it's rotation, these Colt's will have finish wear almost all the way around the cylinder like S&W's do.
The design of the hand in these revolvers is also more S&W-like, in that LENGTH is not a factor, WIDTH is the critical dimension.
For this reason, these revolvers seldom develop "hammer's cocked, but cylinder isn't locked" problems.
The old Colt's were checked for tight lock up by pulling the trigger and holding it back to check for a solid cylinder lock up.
These newer revolvers are not checked with this method since the cylinder MUST be slightly loose with the hammer cocked to allow the bullet passing from the chamber to the bore to force the chamber into alignment with the bore.
Some cylinders may feel tightly locked but enough backlash is built into the action to allow it to move when fired.
Unlike the older Colt's, these guns are designed to have parts replaced, and CANNOT be re-fitted or re-tuned. If they have a problem, new parts are installed.
Also unlike the old Colt's, parts cannot be altered or even polished much. The parts are sintered steel with a thin, glass hard coating.
Any attempt to polish, heat and bend, or alter parts will break through the coating, destroying the part.
As you can see, the timing is much less critical here, and you live with what ya got.
Tuning for a better trigger is limited to installing spring kits, and NO re-fitting of worn parts.
To make up for all this, you get what Master Gunsmith Jerry Kuhnhausen believed was the strongest mid-frame revolver ever built.
So, the bolt should retract before the cylinder begins to rotate.
The bolt should drop back onto the cylinder before the trigger gets too close to the end of it's movement, the sooner the better.
The bolt should lock the cylinder before the hammer gets even close to cocked in single action or before the hammer drops in double action.
If there's a problem of any kind, the action CANNOT be re-fitted or repaired by normal methods.
If there is a problem, the ONLY "fix" is parts replacement.
These actions are assembled and repaired by selecting a part from a bin, and test fitting it.
If it doesn't fit, another part is selected.
This makes it tough for local gunsmith's who don't HAVE a bin full of parts and can lead to him stoning parts to make them fit. This ruins the part which may not become apparent until the part wears.
For this reason, if you have a problem, send the gun in to Colt for a proper repair.
...but It doesn’t take many rounds at all to put those rings on the cylinder, so I wouldn’t put much stock in using that as a tool to determine if it has a lot of rounds through it. That’s the case with the three stainless revolvers that I have anyway, I don’t own anything nickel plated but assume that the resulting carbon rings from a few cylinders fired through it would have simliar marks.
