Cylinder Lockup Timing Check

[TheTinMan]

I came across a post by dfariswheel with detailed instructions on how to check the timing on older Colt revolvers (pre-1969)
Colt Revolver Timing Checks

All four of my Colts checked out fine in terms of cylinder unlocking and bolt drop timing. However, the results on the "cylinder lockup" test were ideal on only one. My Model 1917 has the bolt dropping into the cylinder notch at exactly the same time the hammer is fully cocked. I couldn't get it to cock without the bolt dropping however, no matter how hard I tried.

With both of my Officers Models (1960 OMM and 1937 "38"), if I cock the hammer slowly it is possible to get it to full cock without the bolt dropping into the cylinder notch. I can rotate the cylinder a tiny bit and hear the bolt drop while holding the hammer all the way back. They both "fail" the test (assuming I understood it correctly). If I cock the hammer by pulling the trigger back and catch the hammer all the way back, both guns consistently go into full cylinder lockup.

So what does this mean? Shooting these revolvers double-action is a bad idea?

Do they need to be repaired? I am guessing that trying to repair the problem myself is not an option, but what usually is involved in fixing this problem?

Would it be worthwhile to send both revolvers back to Colt? Anyone know a qualified Colt gunsmith in Virginia who would be an option?

BTW neither gun seems to have been shot much. Actually, the Officers Model Match looked virtually brand new when I got it. I mention that because I don't know if this is something that might resolve itself as the gun breaks in.

One last question: when the hammer is fully cocked without touching the trigger and the bolt is seated in the cylinder notch, the cylinder has a little bit of rotational movement possible. However, if I pull the trigger back the cylinder locks up tight, apparently before the hammer is released. What is the trigger engaging to achieve that lockup?

[A1A]

This is usually the indication of a slightly worn (lower) hand and technically is out of spec. However, many consider this quite normal if only because it is quite common. In most cases, the cylinder momentum from normal rate cycling will carry it to lockup when cocking in SA or before the hammer falls in DA. If they were to shave lead, for example, one would definitely deem them in need of repair. It is within the realm of DIY in that the usual first remedy is to stretch the hand and refit it. However, it is also easy to fracture the hand, if it has already been stretched once or is not done properly, and require replacement and fitting. There are some previous threads. A search on stretch should find some.

When the trigger is fully pulled, it causes the "lower" shelf on the hand to push the cylinder snugly against the bolt for lockup.

[capstan]

I'm not sure I understand exactly the details you are describing.But, it sounds like on the one gun, the bolt is dropping in the cyinder notch when the hammer is all the way back and on the others, the bolt is dropping before the hammer is all the way back,but isnt quite getting into the notch,when the hammer is all the way back. The bolt should drop at about the middle third of the lead/groove,while cocking,before actually falling into the notch. Then just when the hammer is all the way back, the bolt should fall into the notch. Then, when you pull the trigger AND HOLD the trigger all the way back,the gun should lock up tight. That is, with the trigger held all the way back, the bolt should be in the notch and there should be NO movement of the cylinder,whatsoever. You can check this by keeping the trigger pulled all the way back, and with your other hand, check that the cylinder does not move.
Sometimes, the bolt will drop a little early, and it wont quite get into the notch until the trigger is pulled. In most case, it will then, fall into the notch upon pulling the trigger. This is accomplished by the second stage/ lower finger of the hand which pushes it into bank vault lockup.
I had one V spring revolver where the lower finger/second stage of the hand still did not lock it up. On this one I had to stretch the hand. On others where the bolt dropped early or late but still locked up fully upon trigger pull, I fine tuned them anyway to get the bolt to drop in the middel third of the lead DURING cocking,by bending the bolt tail either inward or outward depending upon the condition. To be in perfect timing, the bolt should drop very close to the middle third During the cocking mode,and of course be in full (no cylinder movement) lockup after the trigger is pulled.

[TheTinMan]

Capstan - thanks for your post.

To clarify: On all 4 guns, the bolt clears the cylinder and then drops before the hammer is all the way back. Location when it drops is within the "middle third" of the lead/groove.

With the Model 357, the bolt clicks into the cylinder notch just before the hammer is all the way back. Good to go.

Pulling back the hammer on the Model 1917 results in the bolt clicking into the notch simultaneously with fully cocking the hammer (IOW all the way back). Of course, the monster spring tension in that gun makes gradually cocking the hammer a challenge.

On the two Officers Models, it is possible to fully cock the hammer without the bolt clicking into the cylinder notch. Pulling the trigger seems to complete lockup, but I now know that this isn't exactly right. I have to pull the hammer back very slowly and carefully on the OMM to get the hammer completely cocked without the bolt clicking into the cylinder notch and even then it doesn't happen every time. With the Officers Model 38, I don't have to try and it happens every time. Also, there's more cylinder rotation needed to get the bolt into the notch.

Sounds like 3 out of the 4 are OK, but the Officers Model 38 needs a longer hand.

[capstan]

On the one that doesnt quite make it into the notch, does it then go into the notch when you pull and hold back the trigger? If it does, then you may not need to do anything to the hand, you may only need to adjust the bolt tail to drop later by bending it inward. I have done this on a few and they drop into the notch now with hammer back.
If you havent done this before,it is kind of tedious work. Good luck- sounds like the others are functioning fine.Even the one that doesntgo into notch, may still shoot fine IF the second stage of hand still locks it up. That is
one of the advantages of the oldv spring action. The bolt can drop a little early or late and be technically somewhat out of time yet still function properly at ignition due to the second stage of hand which (usually) pushes the cylinder into full lockup just before the firing pin hits the primer. With my Smiths, if they are slightly out of time and bolt (cylinder stop ) is not in notch when the hammert is back, it STILL IS NOT in the notch when the hammer drops. There is no second stage of the hand with the Smiths.I have a Smith model 629 that has that issue now on a couple clyinders. Ive got to get to it and fix it before I shoot it again because it will not shoot as accuractely as it did, and due to the nature of its action, it is an immediate problem when the bolt does not go into the notch with hammer back. Another reason that I like the Vspring/rebound lever action.

[rhmc24]

A fix I have used on New Service Colts is to solder a strip of tin can on the lower step of the hand. I brighien that top flat of the hand, cut a strip of tin can (iron not aluminum) about 3/32" wide, brighten it, tin it and solder it on so as to add its thickness to the hand. Then trim the excess away around the sides.. I use the 3% silver solder. The added material is in compression and not subject to stress and can last quite a while. It is easy to do again if need be and there is no modification to the original hand. The thickness of the added material may have to be reduced if the original problem is not bad. I have used it on some advanced cases and the thickness has been about right.

[TheTinMan]

capstan - yes, pulling the trigger back does rotate the cylinder so that the bolt clicks into the cylinder notch. I'll have to look up bolt tail adjustment in my Kuhnhausen book and also re-check where the bolt is dropping in the cylinder groove (not "notch").

After studying the Kuhnhausen excerpt above, looking at the hand, and finally understanding that the hand effectively has two chances to fully rotate the cylinder into position, I've got a question about stretching the hand. Given the location of the peening/stretch area, wouldn't stretching the hand move both the top of the hand AND the lower shelf? If the lower shelf is doing its job - locking up the cylinder as the trigger is pulled back - wouldn't raising the lower shelf be "bad"?

[dfariswheel]

No. It's the lower shelf that pushes the cylinder into final lock up and also forces the cylinder into tight lock up.
The upper part of the hand starts cylinder rotation but it doesn't complete the rotation to fully cylinder lock.
When the trigger is pulled, it's the lower shelf that is pushing on the cylinder ratchet.

This is the old Colt "Bank Vault" lock up.

It is possible to over-stretch the hand and cause problems, so stretching is done carefully with lots of test fitting.
The trick is to do an experienced look at the hand and try to get the stretch just right the first time. Too much stretching can cause cracks or broken hands.

Ideally, you'll get the stretched hand just the tiniest bit too long, then seat the hand by removing the rear sight, cocking the hammer and pulling the trigger back, then using a clean rawhide mallet to give the the top of the frame a rap to seat the hand.
This is pictured and described in the Kuhnhausen book.

[RDak]

Guys, I'm not understanding this one.

I have never had a Colt where I could cock the hammer slowly and the bolt would not pop up into the cylinder notch.

If I could do that I would assume something is wrong with the timing? Am I out in leftfield on this one?

[TheTinMan]

Guys, I'm not understanding this one.

I have never had a Colt where I could cock the hammer slowly and the bolt would not pop up into the cylinder notch.

If I could do that I would assume something is wrong with the timing? Am I out in leftfield on this one?

No - not in left field at all. That was the whole point of my questions. The bolt doesn't pop into the cylinder notch on my Officers Model 38 pretty consistently even cocking the hammer steadily. If you cock it fast, inertia keeps the cylinder moving far enough.

dfariswheel - thanks very much for getting me straight. It's very difficult to see the hand engaging the cylinder ratchet pawls, but I see now that it is the "lower shelf" that gives the cylinder the last push to where the bolt clicks into the cylinder notch.

Stretching the hand sounds like a risky proposition, especially for someone who has not been inside a Colt revolver before. Smith & Wessons look like child's play compared to the "everything has at least 2 if not 3 functions" inside the Colt action.