Colt revolver loose crane and cylinder lockup

[FIVETWOSEVEN]

I was at a gunshop a month ago and found a Colt 1917 .45 ACP revolver for around $500-600. It was in dire need of refinishing but it also had sloppy lockup. I'm not too familiar with Colt revolvers but what would it take to tighten one of these revolvers up? After a quick google search, It appeared that I could find replacement parts fairly easy but does it need custom fitting for this old military sidearm?

 

[BBBBill]

Yes. The old Colts are best left to one of the very, very few skilled Colt specialists. All parts must be fit to work harmoniously by someone who knows his business. As there are no new parts being made, old parts may have to be modified to fit (welding/machining) or even made from scratch. If you get really lucky you might find a part that just drops in and functions correctly, but then again sometimes the novice things are fine when, in fact, they are on the ragged edge and may be causing further damage.

Find a genuine specialist for these guns as they are Rube Goldberg-ish compared to the S&W, Ruger, and newer Colt actions.

 

[FIVETWOSEVEN]

Okay thanks for the straight forward answer. I was hoping for a fixer-upper but I'll now have to pass.

 

[tark]

If I remember correctly, you check the cylinder lockup on a Colt differently that the way you check a Smith. Is this true?

BTW we own fast cars for the same reasons we own guns that can shoot more than one shot without re-loading. Bad drivers kill, not fast cars.

 

[243winxb]

If I remember correctly, you check the cylinder lockup on a Colt differently that the way you check a Smith.

Colt locks a split second before the hammer drops, in double action.

S&W lock a lot sooner.

Also , if I remember correctly??

 

[dfariswheel]

Only in the old Colt action models do you check the cylinder lockup by holding the trigger back.
That's not a test for anything in brands like the S&W, Ruger, Dan Wesson, etc or the later Colt's like the Mark III, through Anaconda.

In the S&W and other brands the cylinder does not lock up tightly and is designed to be slightly loose when fired.
This allows the bullet passing from the chamber to the barrel to force the cylinder into alignment.
In the old Colt action when the trigger is pulled the hand forces the cylinder into tight lockup and alignment in what Colt called it's "Bank Vault" lockup.

In S&W and other brands even if the cylinder seems to lock up tightly there's still enough backlash designed into the action to allow the necessary cylinder looseness.
In the old Colt there should be no cylinder movement with the trigger pulled.

Also in the old Colt timing is absolutely critical or the gun just doesn't work well.
In the much less critical other brands the timing can be off and the gun will still function.

The up side of the old Colt action is better accuracy, the down side is the action was much more expensive to build because of the entirely hand fitted and adjusted action requiring highly trained and expensive personnel.
The other brands are much less expensive to build because the action is simply assembled by lesser skilled people. Down side is less accuracy.

 

[FIVETWOSEVEN]

My question now is the crane itself felt more loose than most revolvers I've handled. Would that tighten up with the trigger pulled?

 

[grouselips1]

The crane will not have any "slack" taken up by pulling the trigger. Think of the range of motion of the crane. No clearance should change at any point of movement throughout it's entire range.

 

[grouselips1]

Only in the old Colt action models do you check the cylinder lockup by holding the trigger back.
That's not a test for anything in brands like the S&W, Ruger, Dan Wesson, etc or the later Colt's like the Mark III, through Anaconda.

In the S&W and other brands the cylinder does not lock up tightly and is designed to be slightly loose when fired.
This allows the bullet passing from the chamber to the barrel to force the cylinder into alignment.
In the old Colt action when the trigger is pulled the hand forces the cylinder into tight lockup and alignment in what Colt called it's "Bank Vault" lockup.

In S&W and other brands even if the cylinder seems to lock up tightly there's still enough backlash designed into the action to allow the necessary cylinder looseness.
In the old Colt there should be no cylinder movement with the trigger pulled.

Also in the old Colt timing is absolutely critical or the gun just doesn't work well.
In the much less critical other brands the timing can be off and the gun will still function.

The up side of the old Colt action is better accuracy, the down side is the action was much more expensive to build because of the entirely hand fitted and adjusted action requiring highly trained and expensive personnel.
The other brands are much less expensive to build because the action is simply assembled by lesser skilled people. Down side is less accuracy.

I beg to differ or start any conflict but we are talking potential safety here. Your explanation of smith and wesson action cycling is incorrect as the passing of the bullet does not align the cylinder with the forcing cone(barrel). If that were to occur, you would shave the bullet and thus you are shooting an out of time revolver. That is what range rods are designed to check, cylinder to barrel alignment and also timing. If there are any doubts, call an experienced smith or reference Jerry Kuhnhausens books.

 

[dfariswheel]

I AM an experienced pistolsmith....or was, I'm retired now.
My specialty was Colt DA revolvers, but I also did S&W, some Ruger, some Dan Wesson.

When I say that the S&W. Ruger, Dan Wesson and newer Colt revolvers leave the cylinder loose so the bullet can force the chamber into alignment, I don't mean the cylinder is loose enough to shave lead.
The amount of looseness is very slight.

The old Colt action models were famous for having better average accuracy then the S&W, and the old Colt target model revolvers held all the records back in the revolver days.
That was because the Colt action forced the chamber into perfect alignment with the barrel and the bullet always entered the bore centered.
That meant the bullet wasn't deformed at all so accuracy was better.
In the old Colt's, (within reason) the harder the trigger is pulled the tighter the cylinder is locked in place.

The S&W was slightly less accurate on average because the bullet never entered the barrel centered.
Since the slightly loose cylinder design allowed the bullet to strike the forcing cone just slightly off center the bullet got deformed slightly and accuracy wasn't as uniformly good.
In the S&W and other type actions, the cylinder is as tightly locked as it's going to get when the hammer is cocked, because the hand or pawl in S&W terms by-passes (slides past) the ejector ratchet.
No matter how hard the trigger is pulled the by-passing pawl can't force the cylinder to lock up any tighter.

That slight amount of looseness at ignition allows the bullet to center the chamber with the bore, and that makes the action a lot cheaper to build because it requires almost no fine hand fitting like the hand built Colt action did.

Of course, since the amount of looseness is slight, the cylinder will move enough to allow a range rod to enter the chamber on a properly tuned revolver unless the action is pretty well wrecked.
In the old Colt action, if it's alignment is off and the trigger is held back a range rod will not enter the chamber.
It can't because the cylinder is locked in place whether it's in adjustment or not.

 

[grouselips1]

Sorry, been a busy week! I agree that there are drastic differences in the design of the action, method of locking the cylinder and timing between the two.

From a historical perspective, colt had a large piecer of the market than smith and wesson, prior to WWII. Once you reach the 50's, their factory support for both law enforcement, gunsmiths and competition was almost non existent and their market share began to slide rapidly. The simple numbers regarding market share and thus popularity are why the "old" records on accuracy favor colt. Just because more were being shot at that time. They are not any more accurate on average, than a smith and wesson and 99% of shooters will never see the difference between the two. For myself, I have always shot my best one handed groups with a first generation Trooper and a Python. I attribute that to grip shape. While in two handed shooting, IDPA and Steel, the smith is what I favor. Personal preference here, not fact for every other shooter.

For those who may not understand the functional aspects, lets discuss how the two work. Smith and Wesson. During double action cycling; when the trigger is pulled, the front of the trigger (internal), will pull down the cylinder stop which engages the notches in the cylinder. Simultaneously, the the double action sear face cocks the hammer (compressing the main spring) and moving the hand up, where it contacts the cylinder ratchet, indexing the cylinder. When the trigger moves rearward, it compresses the spring in the rebound slide. The main spring provides the stored energy to propel the hammer with enough force to detonate the primer. The spring in the rebound slide provides the stored energy to reset the trigger. The cylinder ratchet is what controls the timing. It is rare to see wear or damage to the hand a smith. The cylinder stop may be slightly off time but that mainly results in heavy drag marks on the cylinder or a sluggish feeling double action due to excessive friction. Another important note is that the cylinder is locked both front and rear. The cylinder bolt anchors the rear of the cylinder, while the locking bolt under the barrel anchors it at the end of the ejector rod.

When I have time later, I will detail colt function and then finish the comparison

 

[grouselips1]

Now the Colt on the hand is a different animal. When the hammer is cocked, the v shaped mainspring is compressed and the rebound lever moves as well. The hand is attached to the trigger but in a different manner than a smith. The initial engagement of the hand to the cylinder ratchet is on the very top of the hand, which is first engagement surface that begins cylinder rotation. The cylinder bolt is also pulled down, to allow the cylinder to rotate. The secondary or lower notch on the hand is what locks the cylinder in place for the shot by engaging the ejector ratchet. This is why timing is checked on a Colt, with the trigger depressed (as you indicated prior).During the action cycle, the rebound lever moves the cylinder bolt to allow cylinder rotation and then lock up at the end of rotation. It additionally is the link between the v type main spring and the trigger to provide spring force to reset the trigger. There is a diamond shaped "protrusion" on the back of the rebound lever that engages the hand. The cylinder is not locked both front and rear like a smith. Only at the rear and in the cylinder notches. For comparison, a Ruger Super Redhawk cylinder locks front, rear and at the crane. I have seen many Colt's out of time. Very delicate in some respects and the interplay between the hand, cylinder bolt, rebound lever and ratchet are complicated. There are at least a dozen fitting and adjustments that come to mind on these parts.

In regards to your second post, thank you for clarifying the statement. I still think we may disagree on some small details, but good debate gets the mind in action!!

As a synapsis to the originator of the post, yes, you need a skilled, colt experienced gunsmith. No doubt about that!

 

[4v50 Gary]

Send it to Cylinder and Slide. Bill Laughridge's crew knows how to work on them. BTW, lightening a trigger is secondary to ensuring that a trigger is smooth. If you lighten the spring, you can reduce its reliability with various sorts of ammunition. I'd go for reliability first.

 

[4v50 Gary]

In the Double Action mode, as the trigger is pulled rearward, the hand is raised. The finger of the rebound lever rests on the pivot pin of the hand. So, as the hand rises and engages the ratchet of the cylinder, it carries the rebound lever upward and causes the tail of the bolt to pivot upwards. Resultingly, the bolt drops, disengaging it from the cylinder and allows the cylinder to be rotated by the hand. Concurrently, the safety lever is raised (by the trigger) causing the safety to slide downwards. The trigger nose now begins to engage the sear, allowing the hammer to start its rearward motion. When the hand rotates the the cylinder 1/2 to 2/3 of the point of indexing the next chamber, the bolt tail falls off the rebound lever shelf. The bolt is then forced upwards by the bolt spring, resulting in the bolt engaging the leading notch of the cylinder. The cylinder is then arrested from further rotation by the bolt which engages the cylinder notch. The trigger nose continues to raise the sear. When this happens, the hammer is forced forward by the pressure acting upon it from the rebound lever. The mainspring supplies the pressure for the rebound lever. The hammer falls on the frame mounted and spring loaded firing pin, which strikes the primer; thereby compressing the anvil in the primer. The crushing of the anvil grinds the primer compound to 300 degrees, thereby causing ignition. The flash travels through the primer hole into the chamber of the case, igniting the propellant. The gases formed by the propellant dislodges the bullet from the case. The bullet then begins its journey which will take it from the cylinder, past the barrel cylinder gap, through the forcing cone, down the barrel and eventually out of the muzzle.

As the trigger is released, the hand begins to lower and disengages itself from the cylinder ratchet. This permits the rebound lever finger to follow the hand downwards. As the rebound lever lowers, the shelf of the rebound lever forces the bolt tail raised. The trigger nose pushes the sear inward (towards the hammer) and an audible click can be hard as the trigger disengages the sear and allows the sear to return to its position of rest. The safety lever is lowered, allowing the safety to rise. The hammer is pulled away from the firing pin by the mainspring. The bolt tail now pops back onto the shelf of the rebound lever and another audible click is heard. The trigger is now returned to its position of rest by pressure from the finger of the rebound lever. The hammer returns to its position of rest by both the mainspring and a camming action from the rebound lever against the seat of the hammer.

A word of caution on working on your own Colt I frame gun. Some guns have parts which performs a single function. On the Colt I or D or E frame guns, a part may perform numerous functions, all of which relates to timing. Changing one part may affect the timing of several other parts. This is especially true of the Rebound Lever. So, whereas one problem may be corrected, two or three others may have been created. Also, consider the cheapest alternative first which allows for restoration to status quo ante. Bending a part as a solution which you find doesn't work may be resolved by bending it back to its original shape. Removing metal may sometimes be remedied by lengthening by peening; the operative word is sometimes. Since Colt uses 4140 steel for its parts (on D, I and E frames), this allows for peening and shaping by filing/stoning to restore function. On a Colt, you should rarely need to replace parts. If a task appears too daunting, send it to a gunsmith.

So, with those words of advisory out of the way, let us begin by defining a common thread: definition. Unlike the cylinder stop of a S&W or Ruger revolver, the bolt on a Colt (D, I and E frame) is rather lengthy. We'll refer to the "cylinder stop" portion of the bolt as the bolt head and the opposite end which rests on the rebound lever shelf as the "tail". The actual tip of the tail will be referred to as the actuator.

With that, let's look at some ways to delay the bolt from popping up too early.

Recall from Part I how the hand raises the rebound lever and that that action causes the bolt to pivot downward and disengage from the cylinder notch. If you increase the time required for the rebound lever to rise, you delay the bolt's pop. This may be achieved by removing metal from the radius of the pivot pin of the hand. We're talking about removing metal from the top where the rebound lever finger rests on that pivot pin. The end result is that the rebound lever sits slightly lower, thereby taking more time to rise. Doing this should not affect the dropping of the bolt.

Another alternative is working on the bolt itself. As you recall, the bolt tail rests on the rebound lever shelf. If it's been bent previously such that it cants away from the rebound lever shelf. From a top view looking from the top of the gun towards the bottom of the grip, if the tail appears bent towards the solid side of the frame as opposed to the sideplate side, then the bolt tail and actuator sits more precariously on the rebound lever shelf, shortening the time it will rest on that shelf before dropping off (and allowing the bolt to pop up). The bolt may be placed in the vise and with only the tail exposed, grasp with a plier and tweak it (top view again) slightly to the left. This will increase the actuator's contact with the rebound lever shelf, thereby giving you a little more time.

Another thing we were taught was that the main spring could have been weakened, and that increasing spring tension could affect timing of the bolt.

I've also worked on a Colt Official Police. It has the same lockwork as the Python. It needed a new bolt and after it was fitted, the gun had more issues. The trigger was not returning because the bolt wasn't climbing back on the rebound lever shelf. I bent the rebound lever and then polished part of the shelf. I also polished to bolt tail and that only helped a little. The hand was polished to remove any scratches or burrs. My teacher diagnosed the problem back to the rebound lever. The rebound lever also pushes the hammer back, causing the firing pin to retract from the primer. It does it two ways. First is the mainspring which helps pull the hammer back. The second (and why it hung up) was that it pushes at the back bearing surface of the hammer, causing it to rotate back to its position of rest. The rebound lever had been worked over, removing too much metal from it thus not having the surface area to push on the hammer. The cheap quick fix (because no new rebound levers are to be had) was to file down the hammer block at 45 degrees, leaving only 1/2 of its contact surface to block the hammer. Now on Monday I have to lengthen the hand so it will rotate the cylinder earlier.

Finally, if these measures don't work, then fitting a new bolt may be in order. Alternatively, the rebound lever may have to be replaced (and may have been the culprit all the time). If it comes to either two, I'd recommend sending it to a gunsmith or back to Colt.

Notes on the hand: Like the Colt SAA, there are two steps in the hand. The top step initiates the rotation of the cylinder and the lower or second step completes the rotation. The top step should be inclined towards the center pin. If it doesn't, it can cause drag when the second step takes over the rotation. Also, the lower/second step should also be slightly inclined towards the center pin. The belly of the hand should not be so fat so as to push the first step away from the ratchet. With the side plate off, you can watch the hand move as it enters the hand window. It should begin from a retracted position and as it rises, then engage the ratchet. Near the hand's pivot pin you will notice that there is bevel for the finger of the rebound lever. If the two mate perfectly or close to perfect, then the finger will drag on the hand and could possibly prevent the trigger returning to position of rest when the trigger is release (sticky trigger). Polish the finger (not file) and you can gently file to alter the angle of that bevel on the hand.

Cylinder Disassembly: You need a special tool to grab onto the rachet. Brownell's sells it. Push the extractor to give full exposure to the ratchet. Then rotate it so you can unscrew the ratchet. Remove the ratchet. You now need another special tool to disassemble the cylinder screw.

 

[Mizar]

With that, let's look at some ways to delay the bolt from popping up too early... The end result is that the rebound lever sits slightly lower, thereby taking more time to rise. Doing this should not affect the dropping of the bolt...

Would you please explain, because I'm confused here? First you said, that the bolt needed to drop late and then you explained that your alteration did not affect bolt dropping. You needed the bolt to drop late, but all you did was delaying the bolt from clearing the cylinder - which is never an issue. BTW, if you only altered the top of the rebound notch of the hand, leaving other surfaces intact, the rebound lever will rise to the same position as before - i.e. it will take the same time to rise, but more distance to travel.

...It needed a new bolt and after it was fitted, the gun had more issues. The trigger was not returning because the bolt wasn't climbing back on the rebound lever shelf. I bent the rebound lever and then polished part of the shelf. I also polished to bolt tail and that only helped a little...The rebound lever had been worked over, removing too much metal from it thus not having the surface area to push on the hammer...

Why did you bend the rebound lever when the problem was elsewhere?

...Finally, if these measures don't work, then fitting a new bolt may be in order...

I'm lost here - you just fitted a new bolt to that revolver, right? From your words it seems that you either didn't fitted it right, or you are not sure what the problem is.

I am NOT picking you, or try to make fun of you - I really don't understand the explanation of these problems and would like to learn.

Best,
Boris

 

[grouselips1]

Bravo Gary!! Excellent description.

Mizar, Your questions are valid, as this is a complicated set of steps. To help understand Colt revolver function, two things really assisted me. Taking the gun apart, under the supervision of an experienced Colt pistol smith and then referencing Jerry Kuhnhausens book later on, after I had some working knowledge. I agree with Gary, send it out!

 

[Mizar]

grouselips, my questions are valid not because I don't understand the complicated Colt action, but because those "solutions" did not address the original problems.

Best,
Boris

 

[grouselips1]

Mizar, I think they do answer the original post, as "loose" is a general term. But when lock up is noted, he is stating that the gun is indeed out of time and there are many causes for that.

 

[Mizar]

I'm discussing post #13 only and the repairs mentioned for specific problems, nothing else. Let me explain:

...ways to delay the bolt from popping up too early...This may be achieved by removing metal from the radius of the pivot pin of the hand. We're talking about removing metal from the top where the rebound lever finger rests on that pivot pin...

If bolt dropping early is the only problem and everything else is fine, then lowering the rebound lever at the start of it's travel will do exactly nothing. The only thing you will "gain" is delayed bolt pick up. Only lowering the entire rebound lever's position can delay bolt drop off, but then you can end up with insufficient travel to release the bolt, or the bolt tip not clearing the cam completely. And a delayed bolt pick up. Furthermore, you can't make it move slower - in the first instance, lower starting position, it will actually move faster, because it must travel longer distance for the same time. In this condition, if fitting a new bolt is not an option and bending it towards the rebound lever does not correct the issue, the only thing you can do is to stretch the rebound lever compensating for worn-out cam surface/bolt tip, so the cam picks up the bolt tip slightly forward thus dropping it later. And fitting rebound lever height and hammer seat because they will change.

I've also worked on a Colt Official Police....It needed a new bolt and after it was fitted, the gun had more issues.

Those issues (altered hammer seat & sticky trigger return) did not manifest themselves after the new bolt was fitted - they were there to begin with and should have been addressed first. Again - stretching the rebound lever and fitting it will be a better solution then filing the hammer block. Only after correcting those problems a new bolt should be fitted.

Those are just my observations. Again - I am not picking on anyone, but the explanations in post #13 do not sound right to me.

 

[Jim K]

I tried to read all the posts, but this struck me:
"The finger of the rebound lever rests on the pivot pin of the hand"

No, it doesn't. The rebound lever rests on a surface machined into the inside of the hand, not on the pivot pin itself. That surface not only provides a seat for the rebound lever but is set up so the rebound lever cams the hand forward so a separate hand spring is not needed. It is points like that that make the Colt action appear so simple with few parts - until you examine just what those parts do. The only other gun I can think of that ha so many multi-function parts is the M1 rifle.

Jim

 

[Mizar]

I believe he just misnamed the cam of the hand - even a quick look at the internals will show, that the rebound lever could not do it's job (part of it's jobs...) if resting on the pin.

 

[FIVETWOSEVEN]

I went back and looked at that Colt today since I learned that they lock when the trigger is pulled and it locked up like a vault. The finish is very poor but the bore looks amazing and the lockup actually seems very solid. I think I'm going to buy it but I want to make sure I give it a thorough inspection. What needs to be checked before buying a 1917 Colt?

 

[4v50 Gary]

I went back and looked at that Colt today since I learned that they lock when the trigger is pulled and it locked up like a vault. The finish is very poor but the bore looks amazing and the lockup actually seems very solid. I think I'm going to buy it but I want to make sure I give it a thorough inspection. What needs to be checked before buying a 1917 Colt?

Check pitting on exterior and bore
Check lock up on all cylinders.
Range rod it on each cylinder (ensures cylinder to bore alignment).
Check endshake (easy to fix).
Check carry-up on both DA and SA mode.
Check the timing (crucial as this is where the repair expenses come into play).

All comes to worse, you can take the NRA Summer Gunsmithing Revolver Repair Class at Trinidad State with K. Gipson. Gipson was the principal instructor until he accepted the promotion to dean. Of all the teachers there, he knows Colt Pythons and older Colt revolvers. If you polish the action before you get there, you can get it blued while you're there (free for summer students).

 

[dfariswheel]

Old style Colt DA revolvers are why many of us older 'smiths are "twichy" and often grumpy.
I was also a watchmaker so that helped.

Here's my instructions on how to check the timing of the old Colt actions as used in the New Service, Detective Special, Python, etc:
This is valid ONLY for the older pre-Mark III models and no other brand.
Especially, holding the trigger back and checking the rotational movement of the cylinder is NOT a test for anything other then in the older Colt's.

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.

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 LOCKUP.
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.

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 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.

 

[GBExpat]

Niiiiiice.