I thought I'd repost my information on how to check the timing of the older Colt actions.
If you have an old Pre-Mark III Colt, this is how to inspect it for proper adjustment:
To check Colt timing:
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.
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, 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 lead 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 the MIDDLE 1/3rd section 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.
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 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 lead, 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.
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 tuned Colt will:
Have a smoothly functioning bolt with no sticky or hesitant movement.
Unlock before the cylinder begins to turn.
The bolt will drop onto the middle 1/3rd of the ramp.
The bolt will drop into the lock notch before the hammer reaches full cock.
dferriswheel, Great job and very detailed. Just to make certain, it sounds like this procedure is not for newer Colt's. Which ones and why is this not good for all Colt revolvers? I'm just a Colt rookie, so help me understand.
First, when people discuss the classic lockwork Colt's and the transfer bar iginition models the Magnum Carry/SFVI/DSII's don't seem to fit neatly into either category from what I can tell. Is the Magnum Carry something of a hybrid of the two? And if so, how does checking one for proper function differ?
Also, over the years I have heard differing explanations of how similar Colts transfer bar actions are to Smith and Wesson design, with the explanations ranging as widely. I have heard everything from a simple 'not that similar' to the disparaging 'Colt and Wesson' remarks. Are any of those who are able willing to give a genuine rundown of how similar these really are, are these transfer bar Colt's actually the S&W copies they are often accused of being?
The Colt SF is totally a transfer bar ignition/safety system. The only oddity of the SF series is that it uses the older Colt "Vee" spring instead of a coil mainspring.
The action itself is straight transfer bar.
The Colt transfer bar system is totally different than the S&W system, because the S&W uses the original 1890's hammer rebound/hammer block type safety. Colt's older models also used the hammer rebound/block system but Colt's design is different than the S&W rebound/block system.
In short, the pre-1969 Colt and all S&W revolvers made since 1943 have a double hammer rebound and blocking safety system.
When the trigger is pulled the hammer is free to move forward and strike the cartridge. When the trigger is released, the hammer is "rebounded" or forced backward away from the cartridge and is then locked there so it can't move forward again until the trigger is reset and pulled again.
The second safety is a hammer block.
This is a steel bar that's between the hammer and the cartridge. Even if the hammer rebound is broken the safety bar will prevent the hammer from striking the cartridge.
This block moves DOWN in the frame when the trigger is pulled clearing the path of the hammer to move forward and fire.
This type of hammer rebound/block system will work with either a hammer mounted firing pin or a firing pin mounted in the frame.
The key is, the safety systems prevent the hammer from moving forward unless the trigger is pulled and either striking the firing pin, or the cartridge directly.
The transfer bar ignition/safety system is much simpler and probably even safer, but it's the simplicity and lower cost to build that makes it so popular. It's cheaper.
In the transfer bar system the hammer is made in such a way that it cannot contact the firing pin. This is accomplished by having a hole in the hammer face that prevents contact, or projections on the hammer that prevent the hammer from contacting the firing pin.
In any case, the hammer rests on the frame with no possible contact with the firing pin.
Since the hammer rests on the frame, there is no rebounding hammer system.
The action has a flat steel bar or plate that moves UP when the trigger is pulled and puts this bar between the hammer and the firing pin.
When the hammer falls it strikes the transfer bar and that in turn strikes the firing pin, transferring the power from the hammer to the firing pin and firing the gun.
If the trigger is released before the gun fired, the transfer bar instantly drops back down from between the hammer and firing pin and the hammer cannot strike the firing pin.
The transfer bar system can only work with a firing pin mounted in the frame.
The older Colt's like the Python, Detective Special etc and all S&W revolvers use the hammer rebound/block system.
All newer revolvers like the Colt Mark III/King Cobra/Anaconda/SF series and the Ruger, Dan Wesson, Taurus, etc all use a close copy of the original 1969 Colt transfer bar system.
Here's info on how to check timing and operation in the newer Colt transfer bar guns:
CHECKING NEW MODEL COLT TIMING:
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 Mark III/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.
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.
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.
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 past the locking notch, and then drop back onto the cylinder before the trigger gets too close to the end of it's movement.
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 lead to the cylinder locking notch.
Since the bolt rides 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, just like the S&W, Ruger, and most other revolvers. With the hammer cocked, the cylinder is as tightly locked as it's going to get.
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.
There's little tuning beyond 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, including the Ruger's.
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.
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.
For this reason, if you have a problem, send the gun in to Colt for a proper repair.
As you can see, this a far simpler action and is far less "picky" about timing than the older Colt's.
Ferriswheel - I have a couple of questions that Im a little hazy in regarding your info...
First... I have a late 80's 6" matte SS KC. The locking lug in the frame starts to retract at 1/4" of hammer cock and snaps fully extended again at 3/4". In reading your post I got that it should start retracting immediately upon even the slightest of hammer cock. I see no burring of the locking recesses on the cylinder itself though. There is however some wear on the finish between the locking recesses of the cylinder. I have cocked and uncocked the revolver while watching the locking lug to make sure its not dragging and it seems not to be. Is this normal? I'll attach a pic.
Secondly... with hammer down and at full cock there is the slightest, and I mean slightest amount of cylinder play as far as rotation goes. Now when I fire it I dont get any spray of shaved lead or anything like that as if it were firing out of battery. Any thoughts??
I know this is off topic but I cant seem to find a KC link on Proof House. My KC's SN# prefix is CK. If anyone can help me out I'd be much appreciative.
Heres the pic of the cylinder wear...
And please forgive my ignorance if Ive called parts by their wrong names... Im kind of new to revolver speak. Thanks again for your help!
On the later transfer bar safety/ignition guns, the cylinder locking bolt DOESN'T move the instant the trigger is pulled.
That's only for the older guns like the Python and Detective Special, etc.
On the King Cobra, the bolt won't move until the hammer or trigger moves some distance.
How much is not important. All that really counts is that the bolt does unlock from the cylinder before the cylinder starts to turn.
The older Colt's like the Python, Detective Special, etc, had the old Colt "Bank vault" lock up in which with the trigger pulled and held back the cylinder was tightly locked.
The newer guns like the King Cobra are specifically designed not to lock tightly, and holding the trigger back and checking the cylinder is not a valid inspection point.
In these guns, the cylinder is allowed to be slightly loose so the bullet passing from the chamber to the bore will force the chamber into alignment.
This makes the action easier to fit and less expensive to build.
Also, the gun can get out of adjustment and still operate, where the old guns had to be perfect or they just don't work right.
In all cases, how loose a cylinder is with the action at rest is not an issue at all.
As for the line on the cylinder, this is totally normal for the King Cobra and all the later Colt's. The Python and earlier guns "can" be used without getting the line, but in the real world, ALL revolvers will get a line from just opening and closing the cylinder and using the gun.
So, your King Cobra locking bolt just needs to unlock before the cylinder starts to turn and should not start to move until the trigger/hammer has moved some distance.
The cylinder will not lock tightly in place. This doesn't matter if the action is at rest, cocked, or with the trigger pulled.
It sounds and looks like your King Cobra is operating as designed.
This is some great info - Thanks Dfarriswheel!! Is there a sticky on this? If not would it be possible to do it with all this info. Then you wouldn't have to keep repeating it. Just point them to the sticky. I know I'd use it from time to time (no pun intended) to refresh my memory. This info has kept me from buying a couple and got me a good discount on another.
Dfairiswheel:I was just reading over this old post about timing and I have some questions. I guess I'm a little lost...I know in 1969 Colt changed over to a transfer bar system....did this change apply to Detective Specials? I ask because I own a 1977 Detective Special and when I try to move the cylinder with the trigger depressed the cylinder is locked up tight...no movement....I guess my question is what kind of action / bolt does my 1977 DS have?