Another Timing Question

H

hongrn

New member
Folks,

My Pietta 1860 timing is off. As you can see, the bolt is up early and denting the sloped part of the notch on the cylinder. I'm not much of a gunsmith, so would replacing the hammer cure this, since the cam is causing this issue from what I read on this forum? Thanks in advance for your input.

P5280015.jpg


Hong
 
Actually the bolt is dropping just a smidge late not early. The mark should be a little further back in the lead to avoid pushing metal into the notch.
One other thing I noted it looks like your hand is picking the cylinder up just a little early as you have a tick on the outboard side. ie: the hand is trying to rotate the cylinder before the bolt has completely cleared.
 
Replacing the hammer will not do anything. To get the bolt to drop sooner you file a few thousandths off the very top of the leg of the bolt that rides on the cam. To get the hand to pick up the cylinder later file a very very small amount off the top of the hand. Just one or two strokes is normally enough.
To check things. Watch the bolt as you cock it it should drop right in the beginning of the lead in. To check the hand put your thumb and forefinger around the cylinder and bring the hammer back until you just feel the hand start to try to rotate the cylinder. Hold the hammer at this point and try to rotate the cylinder with your fingers. You should feel no resistance meaning the bolt has cleared. If you feel a tick it means you need to take a bit off the hand.

A lot of folks think and a lot of guns are delivered with the bolt dropping right into the notch. This is actually very bad fo two reasons. If you cock the gun fast the cylinder will outrun the bolt and will not lock up. Two with the very slightest wear from use the bolt starts to drop right on the edge of the notch peening it eventually to the point the bolt will no longer enter. Colt put the leads on the cylinder for a reason. Properly timed the bolt will drop into the beginning of the lead. I hope this is clear.
 
Last edited:
Denster,

Thanks for the advice. I will attempt to get this done this weekend. We'll see how this turns out. Have a great weekend.

Hong
 
I second what Denster said.

From the marks on your cylinder it likely is that your bolt is dropping too late and your cylinder is overtraveling before your bolt drops. If your hammer cam was worn out your bolt would be dropping too early instead of too late as yours is. What likely is happening with your revolver is the bolt leg is dwelling on the hammer cam too long. As Denster said you need to remove a tiny bit off the bolt leg (where it rides against the cam) so the bolt will drop sooner. Or as an alternative, you could try removing the cylinder (to prevent ring scoring of it by the bolt) and then cock and recock the gun hundreds of times to wear the bolt leg against the cam. That could help your bolt to wear naturally (without filing it) so that it drops sooner. Filing of course would be quicker but you can also very easily file too much. If you file too much, you have to then try spreading the bolt legs to regain dwell time of the bolt leg against the cam, or else buy a new bolt. So if you file the bolt leg, file carefully and little at a time.

If you file too much your bolt will then drop too early. Like Denster said, you want your bolt to drop in the lead in incline leading to the cylinder notch.

The reason it is most likely your bolt is likely dropping too late rather than too early are several.....

1. The bolt drop wear on the cylinder of your revolver is only evident after the cylinder notch has passed the bolt (evidence of overtravel before bolt drop).

2. If you are wondering if your cam were to be completely worn out if the bolt would drop IMMEDIATELY upon starting to pull the hammer back.....

That would be unlikely because in order for the marks on your cylinder to be like they are just past the notch....your bolt would have to be slipping off your cam immediately....I mean IMMEDIATELY.... just as the bolt rose and the notch cleared the bolt the bolt would fall immediately scoring just past the notch. In order for that to happen your cam would have to be worn to the point that the bolt slipped off it just as the cylinder started to turn. The only way that could happen would be if your cam was almost ground completely away and your bolt leg slipping off it just as soon as the bolt rose and the cylinder just started to turn. Considering the distance (and time it takes) the bolt leg to travel across the face of the cam and drop off, unless your cam were just a fraction of its usual diameter, it would be very unlikely for those marks to be right at the trailing edge of your cylinder like that.

Also in order for those marks to be like that even IF your cam's diameter was worn so badly that the bolt dropped immediately after it rose, for that to happen your bolt leg would have to travel across the face of the cam and then drop....AND remember your pawl is also turning your cylinder while the bolt leg is traveling across the cam. Considering the distance the bolt leg travels across the cam, it would be unlikely that the cylinder pawl would only have rotated the cylinder that teeeny tiny bit before the bolt dropped scoring the cylinder at the trailing edge of your cylinder's notch.

So like Denster said, the culprit is LIKELY your bolt leg dwelling too long traveling across the face of the hammer cam. I say "LIKELY" because sometimes weird wear sometimes happens and sometimes like recently happened to me, an unusual wear or incorrectly hardened part can throw off a diagnosis. Recently I thought the problem was my bolt when my bolt was dropping too early but the actual culprit was the cam. But I don't think that is the case in your situation.




.
 
Last edited:
Denster and Bill,

I'm working on this as we speak, but I don't understand one thing:

1. The cylinder rotates clockwise as I start to cock the gun, so the lead-in groove of the notch reaches the bolt area first.

2. Before the hammer is fully cocked, and the cylinder finishes its rotation, I can hear and see the bolt come up and hit the lead-in groove instead of hitting the notch.

3. This means that the bolt came up EARLY, before the cylinder has the chance to complete its rotation.

4. So, shaving the part of the bolt that rides on the cam only aggravates this issue, since the bolt will pop up even earlier.

Am I correct? I'm so confused. Thank you both for your guidance.

Hong
 
Hong

It is supposed to come up and hit the lead first and ride the lead to the notch which stops the cylinder rotation. That's what I meant when I wrote earlier that many think (wrongly) that the bolt is supposed to drop into the notch. It is not and no part of the bolt should be over the notch when it drops. If it is it will peen the edge of the notch as yours is doing.

One other thing. You don't shave the part that rides on the cam you take some off the very top of that leg essentialy reducing it's height.
 
Denster,

A pic is worth a thousand words for me. So please take a look at this pic and tell me which part I'm supposed to shave off? Thanks a million.

Hong

P5290016.jpg
 
Hongrn wrote:
Denster and Bill,

I'm working on this as we speak, but I don't understand one thing:

1. The cylinder rotates clockwise as I start to cock the gun, so the lead-in groove of the notch reaches the bolt area first.

2. Before the hammer is fully cocked, and the cylinder finishes its rotation, I can hear and see the bolt come up and hit the lead-in groove instead of hitting the notch.

3. This means that the bolt came up EARLY, before the cylinder has the chance to complete its rotation.

4. So, shaving the part of the bolt that rides on the cam only aggravates this issue, since the bolt will pop up even earlier.

Am I correct? I'm so confused. Thank you both for your guidance.

Hong
Click to expand...

Honggrn, if as you say, your bolt drops into the lead in groove then your timing should be correct. But now I am confused. If your timing is correct, then how do you account for the scoring of your cylinder notch's trailing edge? That would only happen if your bolt was dropping too late.

Denster wrote:
One other thing. You don't shave the part that rides on the cam you take some off the very top of that leg essentialy reducing it's height.
Click to expand...

Denster is correct. I poorly worded it earlier. You reduce the height of the bolt leg so it will drop off the hammer cam sooner, not reduce the part that actually rubs against the cam. Take your hammer and bolt out and put them together and look at how the bolt leg rubs across your hammer cam. See how reducing the thickness of the height of the bolt leg will allow it to drop off the hammer cam just a teeny bit sooner? So to answer your question Honggrn, you would remove metal off the bolt leg in area A of your picture.

Here is what is going on as you cock the hammer.

As you begin to cock the hammer the pawl/hand that is attached to the hammer pivots on its pin and raises up in its channel and engages and starts to turn the ratchet on the cylinder. At the same time the bolt leg of the bolt is forced upward by the cam on the hammer. The bolt is under spring tension the opposite direction of how the hammer cam forces the bolt leg upwards. What is happening is the hammer cam is through friction causing the bolt to pivot on its pin against the spring tension of the bolt spring, the bolt leg raising upward on the cam causes the head of the bolt to pivot downward out of the cylinder's notch. Then as the bottom edge of the bolt's rear leg drops off the cam....that frictional tension between the cam and the bolt leg is released and the head of the bolt "drops" or rises up into the lead in groove on the cylinder.

So what Denster said about removing metal off the bottom of the leg (Area A in your photo Hongrn) to reduce its height is correct. NOT take metal off the part that actually rubs against the cam, but reducing the height of the bolt's leg so it drops off the cam a teeny bit sooner.

All the cylinder pawl/hand does upon cocking the hammer, is rise up to engage and turn the ratchet or "star" on the cylinder. Then if rides back down off the ratchet as the hammer is lowered. It will do that whether the bolt is installed or not. The only function of the cylinder pawl/hand is to turn the cylinder.
If you do this with a broken bolt, broken bolt spring, or without a bolt installed, you will notice the cylinder starting to turn the opposite direction just a teeny bit as you lower the hammer. That is because as the pawl/hand rides back down off the ratchet when the hammer is lowered, it can cause a very slight frictional pull of the cylinder in that opposite direction caused by the spring tension of the spring on the pawl/hand as the pawl rides back down off the ratchet. But that can only happen if the bolt has not dropped into the cylinder's notch securely locking it in position.

Basically the pawl/hand has no bearing on the operation of the bolt. The only problem your pawl/hand can cause is if it is too long it will continue to try to turn your cylinder AFTER the bolt has dropped and locked into the notch. Then that can cause a slight wear on the trailing edge of the INSIDE of your cylinder's notch as well as possibly peen the top edge of the pawl as well as peen the ratchet. Conversely, if your pawl/hand is too short, it will not allow your cylinder to sufficiently turn to the point where your bolt leg can drop off the cam and lock the cylinder. This can happen if you cock the hammer slowly. But if your pawl/hand is slightly too short and your very rapidly cock the hammer, the inertia of the cylinder's weight will carry it though its rotation even if the pawl is slightly too short. So to make sure your pawl/hand is long enough, cock the hammer slowly to make sure it's the pawl rotating the cylinder fully instead of rotational inertia carrying the cylinder the rest of the way.

I hope the above explanation helped with understanding.


.
 
Last edited:
Visual Animations

I to get confused as to what is actually going on with the hand, bolt, and cam. Naive question: Are you guys aware of any visuals that could help an old geeser understand the relationship????
 
Cameron,

There's none, that's why it's so hard for newbs like us to understand how things work in a Colt.

Bill, thanks for the clarification. The peening on the trailing edge of the notch is old, and was due to a wide bolt that didn't fit the notch, but I since fixed it. As Denster and you explained, the bolt is supposed to hit the lead-in groove, but is it supposed to hit it that hard and actually dent the lead-in groove as shown in my first picture? So, is the height of my bolt too long then?? Thanks.

Hong
 
Hawg,

I now understand what Denster, Bill and you are saying. Took a while to grasp how the whole thing works. Thanks.
 
is it supposed to hit it that hard and actually dent the lead-in groove as shown in my first picture? So, is the height of my bolt too long then??
Click to expand...

It could be. Some judicious filing on the bolt surface may be in order but go slowly and test function often.
 
Hong

Where A and B intersect that very peak is where you want to remove metal that is lowering the height. The cam runs up A do not remove metal from A only at the very peak and only a small amount.
Hawg the bolt is dropping half in the lead and half over the notch which will peen the edge of the notch. It needs to drop fully in the lead.
 
Hongrn wrote:
As Denster and you explained, the bolt is supposed to hit the lead-in groove, but is it supposed to hit it that hard and actually dent the lead-in groove as shown in my first picture? So, is the height of my bolt too long then?? Thanks.
Click to expand...

That is normal with the bolt spring screw tightened fully. However, to minimize ringing of the cylinder and to prevent unnecessary peening of the cylinder by the bolt "dropping" (raising) with too much pressure, I always decrease the tension on the bolt spring on ALL my revolvers, be they Colts or Remys.

The bolt only needs enough tension to make it "drop" (raise) into the lead in groove to drop into the cylinder's notch. It just needs enough spring tension to make it stay fully up to engage the cylinder's notch. In my opinion, it isn't necessary to have that much tension on the bolt as it comes from the factory. So what I do is this.....

I take the cylinder out so I can see and feel the bolt's head and also remove the trigger guard so I can have access to the bolt spring. Then I back off on the screw holding down the bolt spring that tensions against the bolt. The way I test to make sure I have enough but not too little nor too much tension is by backing off on the spring screw and then pushing down on the bolt head with my finger as it sticks out of the bottom of the frame as if it was locking the removed cylinder. It is totally a "feel" thing. It is also a bit of a sight thing. If when I back off on the spring screw the bolt doesn't come up quite as high as it would if I had the spring tightened down all the way, then I slightly tighten the spring a little more. You want the bolt to come all the way up and not have too little spring tension nor too much.

I continue to tighten or loosen the spring screw until I get the tension on the bolt to where it comes up a high as it should and when I push down on it with my finger...it will pop back up as high as it should....BUT....without unnecessary tension.

Just enough tension to make it come up as high as it should AND NO MORE.
It's a trial and error feel and sight thing but doesn't take very long. You will see and feel how much tension and how much the bolt raises up according to how much you tighten down the bolt spring. Find that happy medium where the bolt comes fully up but without anymore unnecessary spring tension against it than is necessary. Not only will this decrease ringing of your cylinder, but it will also decrease any peening around the cylinder notches as your parts wear. I don't know of anyone else besides myself who does this but it works for me and makes sense. Why have unnecessary tension and therefore unnecessary wear if it isn't necessary? All you need is for that bolt to come to its full height when it "drops" (raises up) and stays at that height even if you push down on it so that it will pop back up to that same height again. Any more tension than that is unnecessary. The cylinder will not ride over the bolt nor push it down because of the 90% angle of the bolt sides to the notch sides. So as long as the bolt goes to it full height when dropped, that's all the spring tension you need and no more.

Your bolt spring will also last longer this way too because it has to flex less and therefore has less fatigue on it.

This way....as the cylinder rotates, the bolt does not have as much tension on it as it did from the factory and it will not exert as much tension against the cylinder which decreases ringing around the cylinder and also will decrease any peening around the notch because the bolt is not using more pressure than it needs to raise. Understand?

Even though my bolt spring is not tightened down fully, I have never needed any lock-tite on it to keep it from turning or unthreading. The spring tension on it serves to keep the screw from moving I think. Kind of like a spring lock washer. I have never had one get tighter nor looser from shooting. Besides usually I tear the revolver completely down (as opposed to just a field strip cleaning after every shoot) quite often and clean it completely after about two or three range shooting sessions. So I readjust the spring tension then anyway.




.
 
Last edited:
Yep, your bolt could drop a little sooner. Ideally it should drop right at the beginning of the lead while being cocked very slowly. Anywhere between the beginning and half way is acceptable. That way the bolt has enough time to engage the slot at fast cocking speeds. At normal or fast cocking speeds, the bolt will then still hit about where it is hitting now, and this would be normal. The problem is that some of those Italian made cylinders are unnecessarily soft.

Changing the bolt spring tension will also affect your trigger weight, so experiment.
 
You must log in or register to reply here.
Back
Top