Barrel / Cylinder alignment

[borne2fly]

I've hand machined quite a few internal gun parts but a new bolt from bar stock would be a real job,especially the fingers, to get right. What I would do is either TIG weld the bolt head wider and mill to fit the enlarged window width then mill the off set on the top end to fit the cylinder notches or more likely silver solder on a laminate of spring stock and mill down to fit the offset notch width.
The spring stock laminate would probably be the way to go and low temp silver solder/sweating it to the upper bolt nose after heat treating. A carbide mill would do the width trim and offset with final fitting via a diamond file.
I like and use a lot of Force 44 low temp silver solder for work like this as it has 2/3rds the shear strength of high temp silver solder and would be more than adequate to the job.

>> … or more likely silver solder on a laminate of spring stock and mill down to fit the offset notch width.

I like that.
Yes, a carbide end mill to get it close then abrasives for the final fit.
And silver solder permits the option of removing the shim without damaging the bolt.
Bicycle frames use to be brazed decades ago. You could fiddle with the fit before letting the joint cool

 

[M. De Land]

>> … or more likely silver solder on a laminate of spring stock and mill down to fit the offset notch width.

I like that.
Yes, a carbide end mill to get it close then abrasives for the final fit.
And silver solder permits the option of removing the shim without damaging the bolt.
Bicycle frames use to be brazed decades ago. You could fiddle with the fit before letting the joint cool

Well the reason for low temp silver solder is so the spring stock laminate and original bolt nose will not be softened by sweating it in place before milling and final fitting with a diamond file.
High temp silver solder sweating (900-1100 degrees F) spring stock laminate to the bolt nose would anneal both bolt nose and the spring stock. Both must remain hard.

 

[Vic]

Last pic shows "tall" side of bolt. It also shows some space that should be plenty to allow bolt to locate in a correct position. You should be able to rotate cylinder backwards with hammer down and have the chamber line up with the bore. If not, bolt width may need to be adjusted.
If you can't do that with the hammer at full cock, that means the hand is a little long.

Funny how the SA revolver is often described as "simple" ( and "number of parts" wise, it is), but there is a LOT of "technicality" involved if one is to run "correctly".

Mike

Thanks! Defenitely need to start with the bolt. But as soon as it locks too late, I think I shall file the short side, to let it drop into the notch earlier.

Here’s hand photo and the video of action from both sides. I don’t think the hand is too long. Just have to cock it all the way back to catch the notch.

 

[M. De Land]

Thanks! Defenitely need to start with the bolt. But as soon as it locks too late, I think I shall file the short side, to let it drop into the notch earlier.

Here’s hand photo and the video of action from both sides. I don’t think the hand is too long. Just have to cock it all the way back to catch the notch.


View attachment 308548View attachment 308550

Do the same thing with some thumb tension on the cylinder which will duplicate fouling build up on the cylinder rotation and changes the timing.

 

[Vic]

Do the same thing with some thumb tension on the cylinder which will duplicate fouling build up on the cylinder rotation and changes the timing.

Nothing changes.

It’s a .36 I didn’t experience any fouling during 50 rounds with some wander lube on cylinder pin.

 

[M. De Land]

Nothing changes.

It’s a .36 I didn’t experience any fouling during 50 rounds with some wander lube on cylinder pin.

Yup, your right, the bolt drops before rotation starts in the video. That must mean that the timing was corrected at the factory when the contact on the back edge was noticed during final inspection, before it was shipped.

 

[M. De Land]

Thanks! Defenitely need to start with the bolt. But as soon as it locks too late, I think I shall file the short side, to let it drop into the notch earlier.

Here’s hand photo and the video of action from both sides. I don’t think the hand is too long. Just have to cock it all the way back to catch the notch.


View attachment 308548View attachment 308550

If you want the bolt to drop earlier than I recommend diamond filing a few strokes off the top of the hammer cam radius being sure to maintain square/90 degrees on top. Take to much and you'll be back to bolt drag on back of the cylinder notch. It's a balancing act between hammer cam, bolt nose height, bolt finger positioning, ratchet teeth and hand length hence Mike's comment about single action revolvers not being as simple as one might think !

 

[Vic]

If you want the bolt to drop earlier than I recommend diamond filing a few strokes off the top of the hammer cam radius being sure to maintain square/90 degrees on top. Take to much and you'll be back to bolt drag on back of the cylinder notch. It's a balancing act between hammer cam, bolt nose height, bolt finger positioning, ratchet teeth and hand length hence Mike's comment about single action revolvers not being as simple as one might think !

Actually I want the cylinder notch to be a little closer to the bolt )) Taking into account, that it’s not realistic, I could file the short part of a bolt.

Above I saw an opinion that I must be able to move cylinder radially by my hand when the gun is cocked. Currently it locks tight. am in a big doubt that I should let it wobble clock and counterclockwise…

 

[M. De Land]

Actually I want the cylinder notch to be a little closer to the bolt )) Taking into account, that it’s not realistic, I could file the short part of a bolt.

Above I saw an opinion that I must be able to move cylinder radially by my hand when the gun is cocked. Currently it locks tight. am in a big doubt that I should let it wobble clock and counterclockwise…

Your right, when the bolt drops into the cylinder notch it should be locked in position with no lateral/radial movement. The bolt must match closely both the widened window width in the frame and the notch width in the cylinder or it will move laterally the same amount of clearance slack.
When the bolt is retracted and the cylinder is free wheeling at the push of the hand nose while cocking it only comes to stop at the bolt drop into the cylinder notch and there should be little if any back lash . The hand no longer is securing the cylinder in the forward direction.
As soon as the hammer begins to drop the pressure is removed from the hand on the ratchet star and only the bolt fit to both the cylinder notch and window is securing the chamber in position to the bore. The hand will still have some spring tension on the ratchet but it isn't locking it in position.
If one makes an offset bolt nose the width in both clearances (window and notch) must still be present but is off set the amount required to align the bore with the chamber. The off set bolt must still fulfill the necessary close tolerance fit to both the wider frame window and offset cylinder notches which aligns the chamber and bore.

 

[45D]

Actually I want the cylinder notch to be a little closer to the bolt )) Taking into account, that it’s not realistic, I could file the short part of a bolt.

Well, you can remove material from the backside of the bolt head to move the contact patch forward. That will give a better or closer to "middle of the notch" engagement.

Above I saw an opinion that I must be able to move cylinder radially by my hand when the gun is cocked. Currently it locks tight. am in a big doubt that I should let it wobble clock and counterclockwise…

With the amount of misalignment in the revolver pictured in this thread, it definitely doesn't need "tight lockup"! The cylinder of a revolver needs to allow the ball / bullet to "self align" with the bore as it passes from chamber to bore. Otherwise leading, degrading accuracy won't get better. In an unmentionable, the pressure spike can be tremendous to catastrophic. Line boring a revolver can allow "tight lockup" but a "production" SA revolver ( including cap guns) will perform best with some "self alignment". I doubt most folks will spend the bucks to Line bore a cap gun or have a custom cylinder made.
I would "adjust" the bolt in yours to correct the alignment . . . that is the biggest problem with it at this point.

Mike

 

[M. De Land]

Well, you can remove material from the backside of the bolt head to move the contact patch forward. That will give a better or closer to "middle of the notch" engagement.



With the amount of misalignment in the revolver pictured in this thread, it definitely doesn't need "tight lockup"! The cylinder of a revolver needs to allow the ball / bullet to "self align" with the bore as it passes from chamber to bore. Otherwise leading, degrading accuracy won't get better. In an unmentionable, the pressure spike can be tremendous to catastrophic. Line boring a revolver can allow "tight lockup" but a "production" SA revolver ( including cap guns) will perform best with some "self alignment". I doubt most folks will spend the bucks to Line bore a cap gun or have a custom cylinder made.
I would "adjust" the bolt in yours to correct the alignment . . . that is the biggest problem with it at this point.

Mike

What is self alignment ? Are you saying the chamber can be off axis in one or both planes in lock up and the bullet will align it self square to the bore given enough bolt fit slack as it passes from chamber mouth to bore ?
My experience has been if a bullet starts cockeyed into the bore accuracy suffers in rifle or hand gun.
Having misaligned chambers in a revolver has the same effect on accuracy as having a loose or sloppy chamber in a rifle, nothing good comes of it.
I had a good friend some years back that specialized in owning and testing Freedom Arms revolvers and he said at that time he had owned and sold about 50 of their guns. He would buy one, wring out the best accuracy he could get and then sell the revolver to try another.
Dennis told me he had owned just three of them that would consistently shoot a minute of angle at 100 yards. Most of their guns would do so some times but only three could be counted on to deliver that accuracy. You won't find any lateral play or misalignment in any of those revolvers like one does in regular production guns.
Dennis was the best benchrest revolver shot I have ever encountered !

 

[45D]

What is self alignment ? Are you saying the chamber can be off axis in one or both planes in lock up and the bullet will align it self square to the bore given enough bolt fit slack as it passes from chamber mouth to bore ?
My experience has been if a bullet starts cockeyed into the bore accuracy suffers in rifle or hand gun.
Having misaligned chambers in a revolver has the same effect on accuracy as having a loose or sloppy chamber in a rifle, nothing good comes of it.

That's exactly what I mean. There's a difference between alignment tolerance and "slop". As I posted, unless you have perfect alignment between bore and chamber along with hard lockup, you're not doing yourself any favors. What you're doing is forcing the deformation of the ball/ bullet. None of my revolvers will show any hint of a crescent in either direction when checking alignment. That in turn means there's nothing anywhere close to "cockeyed".
On page 177 of the Kuhnhausen book there is a warning concerning zero perceptible sideplay when fitting a bolt, especially in a "non-Colt" revolver. The Italian copies are not Colts and perfect chamber / bore alignment is an accident more than the norm.
I will offer that all my revolvers have "aftermarket" cylinders made with high precision being that's the main article . . . that does make a certain advantage as I've seen pics of cylinders in cap guns with grossly spaced chambers that required replacement.

I had a good friend some years back that specialized in owning and testing Freedom Arms revolvers and he said at that time he had owned and sold about 50 of their guns. He would buy one, wring out the best accuracy he could get and then sell the revolver to try another.
Dennis told me he had owned just three of them that would consistently shoot a minute of angle at 100 yards. Most of their guns would do so some times but only three could be counted on to deliver that accuracy. You won't find any lateral play or misalignment in any of those revolvers like one does in regular production guns.
Dennis was the best benchrest revolver shot I have ever encountered !

Precisely my point.
A purpose built revolver can indeed be set up to almost zero tolerance and they are magnificent works of art!!
Italian copies aren't "them" and folks wouldn't pay $2,500.00 for one either. But, I understand what you mean . . .

Mike

 

[M. De Land]

My guess is the reason opening the chambers up to groove diameter or perhaps .001 more may be the reason it generally aids accuracy. The increased chamber mouth diameter is easing the off center delivery into the forcing cone.
I don't have any faith at all in loose bolt fit (self alignment) aiding both axis misalignment no matter what Kuhnhausen says ! Remember me saying I agree with most of what he says but believe he has some ideas wrong ?
Loose bolt slack in the notch allows radial movement but the vertical misalignment remains as solid as the base pin or arbor clearance allows.
The reason a ball handles accuracy better than a square base bullet in misalignment is because of it's hemisphere base not because it's self aligning better.
A bullet hitting the forcing cone out of both axis alignment is being shape distorted and forcing it's flat base out of bore square long before the cylinder mass can react as best it can to align itself in both axis.

 

[Vic]

I don't know of any fix for vertical misalignment except reaming over size to groove diameter or fitting a new cylinder but for horizontal misalignment I would make a new bolt with a wider body and off set head to which ever side was needed. This would necessitate the window to be widened as well to accommodate the wider bolt body that would be offset one way or the other to facilitate alignment. The bolt width must both fit the cylinder notch (bolt nose/top) and window well (lower bolt body) to maintain alignment which is how the wider off set bolt and window would allow this. The increased bolt width is how we get the offset and still maintain cylinder notch width fit.
The cylinder notches are indexed/timed to the ratchet star and hand length so could not be moved.

Thanks a lot ! The easiest and perfect thing for a start is a factory new bolt, no tall side filing. I’m pretty sure that one of the previous owners just “tuned” the wrong side )) and those half mm will be quite enough for the issue in discussion.

Thanks everybody for such interesting information! Will report with new bolt and hand. If they fit, I will be able to shorten the original hand a little bit to prevent cylinder overturning.

 

[M. De Land]

Thanks a lot ! The easiest and perfect thing for a start is a factory new bolt, no tall side filing. I’m pretty sure that one of the previous owners just “tuned” the wrong side )) and those half mm will be quite enough for the issue in discussion.

Thanks everybody for such interesting information! Will report with new bolt and hand. If they fit, I will be able to shorten the original hand a little bit to prevent cylinder overturning.

I'll be very surprised if a new bolt will change the misalignment much if any as the problem is most likely in the cylinder notch positioning. My thinking is a new cylinder will need to be fitted or as has been speculated an off set bolt arrangement built. I would go with the off set bolt myself.
I could always make another,wider bolt to fit the modified window but a new cylinder would be quite expensive.