Revolver lockup problem

Poodleshooter · September 13, 2002, 02:53 PM

I'm once again playing with my "practice" gunsmithing weapon- a Pietta 1858 Remington copy. Currently the revolver has an interesting problem, in that it only periodically locks up properly. The cylinder usually advances too far, then has to be rolled back to lock up against the cylinder stop. The odd part is that I think that to some extent, how far back I cock the hammer affects how far the pawl advances the cylinder-usually too far if I bring the hammer back to full cock swiftly. Where should I start adjusting in order to rectify this issue? I'm guessing the pawl spring may be at fault here, as that was the part that originally failed in the gun-turning it into my hobby gunsmithing weapon.

James K · September 13, 2002, 08:48 PM

In most SA revolvers, the hand can rotate the cylinder farther than is required to lock up. The cylinder stop will (normally) drop (yes, I know it goes up, but the term "drop" is used) into the cylinder notch before the had is at its full reach, so the cylinder is under pressure to rotate after it locks up. This puts excessive wear on the hand and cylinder stop, as well as on the cylinder notch and ratchet.

Ideally, though, three things should happen almost at the same time. The hand should turn the cylinder just to the locking point, the cylinder stop should drop into the notch, and the trigger should drop into the full cock notch on the hammer. When this is right, the revolver is said to be "timed" properly.

If your cylinder is rotating past the point where the cylinder stop should drop, the basic problem is in the cylinder stop, though the hand will also need shortening a bit. The cylinder stop should stop rotation whether the hand has reached its full travel or not.

When the hammer is cocked, the cylinder stop should first be drawn out of the notch it is in, then held down until it drops about 1/4" ahead of the next notch. Its spring should be strong enough to do the job, but most are far too heavy and will mar the cylinder. The cylinder stop part of the spring can be thinned to achieve the right tension.

It is possible that the cylinder stop is not coming up enough, that its spring is weak, or that it is not shaped right.

You can check some of these things with the cylinder out of the frame.

There are several books on tuning the SA revolvers, including one by Kuhnhausen, which is available from Brownells and contains everything you were afraid to ask about single actions.

Jim

Poodleshooter · September 25, 2002, 11:02 AM

Is there a way to cause the cylinder stop to drop earlier? I think this could be done by reducing the height in the 1-3o'clock section of the small circular nub on the right hand side of the hammer, thus causing the cyl.stop to be released from the hammer movement at an earlier time. The spring (combo trigger and cylinder stop spring) is at a fairly high tension, and the stop doesn't seem to be interfered with in any way, it just drops after the cylinder notch passes it. It's actually only missing it by about 1/2 the width of the cylinder stop. The hand is somewhat weakly sprung, but it simply seems to advance the cylinder just a bit too far. My original problem with this gun was when the hand spring broke, so possibly the cylinder stop was too heavily sprung in the first place? Could the travel of the hand be decreased by decreasing the depth of the full cock notch? That would reduce the full range of pivot of the hammer to reach full cock and the attached hand assembly wouldn't travel as far upward. Or should I simply sand down the height of the hand?
I am learning quite a bit about the operation of basic single actions from this exercise. I'm still unclear on all of the ramifications and how-to's of adjusting timing, so I'll wait on some advice before removing metal.
I'd get the Kuhnhausen book, but it costs about 1/2 of what the gun did. Besides, the internet is free!

James K · September 25, 2002, 01:32 PM

Don't mess with the stud on the hammer except to flatten it a bit to remove the excess height that causes the bolt to flex too much. (The hammer is an expensive part. The golden rule is always mess with the cheaper part.)

The bolt should slip off the front of the stud, not the side, and taking a bit (carefully) off the back of the bolt end will let it slip earlier. You want the bolt to drop into the leade of the cylinder stop cuts, not halfway between them. Then trim the side of the double spring that operates the bolt down until the bolt does not dent the cylinder. (Most of those springs are way too strong.) Leave the trigger spring side alone.

As I said, the bolt should stop the cylinder regardless of the hand, but if the hand is still trying to turn the cylinder when the bolt stops it, the chances of both hand and bolt being damaged is great.

This is tricky. But here is what should happen, all at almost the same time: The bolt should drop onto the leade. The hand should continue to turn the cylinder just enough to let the bolt drop into the notch. The trigger should drop into the full cock notch of the hammer. The hammer should stop on the backstrap, so no more force is applied to the internal parts.

If all this is in time, the strain on parts is minimal, and the gun will work perfectly for a long time. If it is not right, there will be a deep gouge in the cylinder, the bolt will break or bend, and the hand and ratchet will wear rapidly.

All of this involves a lot of "cut and try", with the high probability of ruined parts, which is why that sort of work is very expensive if done properly. If someone says he can tune a single action in a few minutes or for a few dollars, he is darned good. Whether he is good as a gunsmith or as a liar will be determined by his work.

Jim

Poodleshooter · September 25, 2002, 03:41 PM

I'll give it a try and post back eventually. Thanks for your time Jim!

September 13, 2002, 02:53 PM	#1
Poodleshooter Senior Member Join Date: August 7, 2000 Location: Floating down the James River in VA Posts: 2,599	Revolver lockup problem I'm once again playing with my "practice" gunsmithing weapon- a Pietta 1858 Remington copy. Currently the revolver has an interesting problem, in that it only periodically locks up properly. The cylinder usually advances too far, then has to be rolled back to lock up against the cylinder stop. The odd part is that I think that to some extent, how far back I cock the hammer affects how far the pawl advances the cylinder-usually too far if I bring the hammer back to full cock swiftly. Where should I start adjusting in order to rectify this issue? I'm guessing the pawl spring may be at fault here, as that was the part that originally failed in the gun-turning it into my hobby gunsmithing weapon.

September 13, 2002, 08:48 PM	#2
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	In most SA revolvers, the hand can rotate the cylinder farther than is required to lock up. The cylinder stop will (normally) drop (yes, I know it goes up, but the term "drop" is used) into the cylinder notch before the had is at its full reach, so the cylinder is under pressure to rotate after it locks up. This puts excessive wear on the hand and cylinder stop, as well as on the cylinder notch and ratchet. Ideally, though, three things should happen almost at the same time. The hand should turn the cylinder just to the locking point, the cylinder stop should drop into the notch, and the trigger should drop into the full cock notch on the hammer. When this is right, the revolver is said to be "timed" properly. If your cylinder is rotating past the point where the cylinder stop should drop, the basic problem is in the cylinder stop, though the hand will also need shortening a bit. The cylinder stop should stop rotation whether the hand has reached its full travel or not. When the hammer is cocked, the cylinder stop should first be drawn out of the notch it is in, then held down until it drops about 1/4" ahead of the next notch. Its spring should be strong enough to do the job, but most are far too heavy and will mar the cylinder. The cylinder stop part of the spring can be thinned to achieve the right tension. It is possible that the cylinder stop is not coming up enough, that its spring is weak, or that it is not shaped right. You can check some of these things with the cylinder out of the frame. There are several books on tuning the SA revolvers, including one by Kuhnhausen, which is available from Brownells and contains everything you were afraid to ask about single actions. Jim

September 25, 2002, 11:02 AM	#3
Poodleshooter Senior Member Join Date: August 7, 2000 Location: Floating down the James River in VA Posts: 2,599	Is there a way to cause the cylinder stop to drop earlier? I think this could be done by reducing the height in the 1-3o'clock section of the small circular nub on the right hand side of the hammer, thus causing the cyl.stop to be released from the hammer movement at an earlier time. The spring (combo trigger and cylinder stop spring) is at a fairly high tension, and the stop doesn't seem to be interfered with in any way, it just drops after the cylinder notch passes it. It's actually only missing it by about 1/2 the width of the cylinder stop. The hand is somewhat weakly sprung, but it simply seems to advance the cylinder just a bit too far. My original problem with this gun was when the hand spring broke, so possibly the cylinder stop was too heavily sprung in the first place? Could the travel of the hand be decreased by decreasing the depth of the full cock notch? That would reduce the full range of pivot of the hammer to reach full cock and the attached hand assembly wouldn't travel as far upward. Or should I simply sand down the height of the hand? I am learning quite a bit about the operation of basic single actions from this exercise. I'm still unclear on all of the ramifications and how-to's of adjusting timing, so I'll wait on some advice before removing metal. I'd get the Kuhnhausen book, but it costs about 1/2 of what the gun did. Besides, the internet is free!

September 25, 2002, 01:32 PM	#4
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	Don't mess with the stud on the hammer except to flatten it a bit to remove the excess height that causes the bolt to flex too much. (The hammer is an expensive part. The golden rule is always mess with the cheaper part.) The bolt should slip off the front of the stud, not the side, and taking a bit (carefully) off the back of the bolt end will let it slip earlier. You want the bolt to drop into the leade of the cylinder stop cuts, not halfway between them. Then trim the side of the double spring that operates the bolt down until the bolt does not dent the cylinder. (Most of those springs are way too strong.) Leave the trigger spring side alone. As I said, the bolt should stop the cylinder regardless of the hand, but if the hand is still trying to turn the cylinder when the bolt stops it, the chances of both hand and bolt being damaged is great. This is tricky. But here is what should happen, all at almost the same time: The bolt should drop onto the leade. The hand should continue to turn the cylinder just enough to let the bolt drop into the notch. The trigger should drop into the full cock notch of the hammer. The hammer should stop on the backstrap, so no more force is applied to the internal parts. If all this is in time, the strain on parts is minimal, and the gun will work perfectly for a long time. If it is not right, there will be a deep gouge in the cylinder, the bolt will break or bend, and the hand and ratchet will wear rapidly. All of this involves a lot of "cut and try", with the high probability of ruined parts, which is why that sort of work is very expensive if done properly. If someone says he can tune a single action in a few minutes or for a few dollars, he is darned good. Whether he is good as a gunsmith or as a liar will be determined by his work. Jim

September 25, 2002, 03:41 PM	#5
Poodleshooter Senior Member Join Date: August 7, 2000 Location: Floating down the James River in VA Posts: 2,599	I'll give it a try and post back eventually. Thanks for your time Jim!