Pietta cylinders slipping out of lockup

[45D]

That's odd, I believe reading Kuhnhausen manuals is were I learned to do what I described. It works on any revolver single or double action ! Smooth/polish the top of the bolt dome so it slides and does not gall the cylinder and just break ( smooth the sharpness with a stone) the corner edge of the dome leaving the sides parallel. This break over on the edge from dome to parallel sides smooths bolt drop into the notches. The notch corners getting the same corner smoothing has the same effect by removing the machining burrs without loosing snug bolt side to side fit in the window or notches.
The last picture in your post shows the bolt dome galling the top of the lead cut into the cylinder notch !

You need to reread your post and then reread the section in the book. p.171 - 175

Mike

 

[45D]

I was looking at some old Colts for sale and lots of them had peened cylinders and drag marks from the bolt. Without mods like @45D does that action is the bare minimum of simplicity to make the cylinder index.

Peening and or scoring is typical of bad timing along with excessive bolt spring tension.

Mike

 

[M. De Land]

I also wonder how many people over the last 50+ years of Pietta and Uberti that just shot these things with slippy lockup , totally oblivious and nothing bad ever happened

I'm going to pick one brasser and fit the bolt to the tightest notch

I also wonder, just out of curiosity, if after lots of shooting, the bolt stop notches and bolt would just break into each other kind of like how S&W stop notches "peened" and lockup got a little sloppy, but they still work fine

I do agree that the bolt dome does not seem to be making contact with the bottom of the notch and would probably recommend reducing the bolt neck height a bit if it's contacting after checking the window and the frame floor for any burrs to make it drop deeper which may cure the problem.
Another possibility comes to mind worth looking at is bolt spring strength or bend.
I've made these mods to all of my personal guns (single and double action) and every one I have worked on for others for many years.............. none of them suffer from what you describe .

 

[M. De Land]

I was looking at some old Colts for sale and lots of them had peened cylinders and drag marks from the bolt. Without mods like @45D does that action is the bare minimum of simplicity to make the cylinder index.

I don't believe I have ever seen any single action other than a Freedom Arms or "Colt drawer Queen" that does not have some bolt drag marks after some real use ! They keep right on working any way in most instances.
Actually I much prefer the look of a properly functioning gun with the blue wore off from use and some smooth drag marks. It's lived and provided some practical use to some one !

 

[Relic shooter]

https://gungiveaways.com/tuning-the-pietta-cap-and-ball-for-competition/

Excellent link on how to tune revolvers

 

[45D]

Excellent link on how to tune revolvers

Larsen's writings are excellent for the most part but the "arbor length test" isn't a good test at all.
The easiest "test" is to just look and see if there's a "witness mark" at the bottom of the arbor hole. If the arbor is making contact, there will be a shiny circular ring.
This way you don't have to remove material from the arbor (creating excessive clearancing) just to get the barrel assy to go on the arbor at 90° . . . there's no need to do that.

You can clearly see the mark left on the spacer I installed.

Mike

 

[maillemaker]

I had an Uberti 1858 that would "jump the bolt" if I cocked the hammer fast.

I found that it only did this with a couple of cylinder notches. To solve the problem, I deburred the notches and made sure that the bolt (removed from the gun) fit all of the notches well by pressing the bolt into the notch with the cylinder and bolt out of the gun.

I noticed that for a couple of the notches the bolt did not seat well. It took only the barest of filing to get it to work.

 

[Billy Boy]

That's odd, I believe reading Kuhnhausen manuals is were I learned to do what I described. It works on any revolver single or double action ! Smooth/polish the top of the bolt dome so it slides and does not gall the cylinder and just break ( smooth the sharpness with a stone) the corner edge of the dome leaving the sides parallel. This break over on the edge from dome to parallel sides smooths bolt drop into the notches. The notch corners getting the same corner smoothing has the same effect by removing the machining burrs without loosing snug bolt side to side fit in the window or notches.
The last picture in your post shows the bolt dome galling the top of the lead cut into the cylinder notch !
The bolt dome corner that's doing this needs to be broke ( smoothed out without loosing profile) .

I stone the top of my bolts with a ceramic stone till they shine and I try to time them so they drop before the lead notch - this helps apply the breaks if cocking fast. A line on the cylinder( not a groove) doesn’t mean it’s out if time.

 

[45D]

I stone the top of my bolts with a ceramic stone till they shine and I try to time them so they drop before the lead notch - this helps apply the breaks if cocking fast. A line on the cylinder( not a groove) doesn’t mean it’s out if time.

Actually, the hand spring supplies the brakes. The bolt should have only 3 -4 lbs pressure ( not much "braking" with that )
( It's all in that same Kuhnhausen book . . . shhhhhhh ).
A "Beauty ring" denotes timing problems,
ill handling or both.

Mike

 

[M. De Land]

I stone the top of my bolts with a ceramic stone till they shine and I try to time them so they drop before the lead notch - this helps apply the breaks if cocking fast. A line on the cylinder( not a groove) doesn’t mean it’s out if time.

I agree , with the hand driving the cylinder forward with increasing speed as per usual hammer manipulation, the slightly increased hand tension from the chimney angle on the hand spring is braking nothing of the cylinder inertia. Great theory though !
The much greater leverage of the bolt contact with the larger orbit of the cylinder circumference does brake the inertia.

 

[45D]

I agree , with the hand driving the cylinder forward with increasing speed as per usual hammer manipulation, the slightly increased hand tension from the chimney angle on the hand spring is braking nothing of the cylinder inertia. Great theory though !
The much greater leverage of the bolt contact with the larger orbit of the cylinder circumference does brake the inertia.

Riiiiiight . . .

( loose yer Kuhnhausen book sir?)
Funny how sometimes he's the "King" and sometimes he doesn't know what he's talking about!!

Mike

 

[Stantheman86]

I sometimes miss the days when I was young , and would just shoot guns and have fun being blissfully unaware of how they worked mechanically . I'll bet my first cap and baller , an ASM 1860, probably had stuff wrong with it but I just shot it, being afraid of the dreaded Chain Fires every gun shop guy warned me about

I mean we have to know how to repair them and make sure they're safe. But I Redneck Remoted plenty of beat up old military rifles then fired them with old surplus ammo, if they worked they worked .

Then I started hyper analyzing everything and now here I am today Learning how to fit bolts from people with more mechanical knowledge than me

 

[Stantheman86]

I had an Uberti 1858 that would "jump the bolt" if I cocked the hammer fast.

I found that it only did this with a couple of cylinder notches. To solve the problem, I deburred the notches and made sure that the bolt (removed from the gun) fit all of the notches well by pressing the bolt into the notch with the cylinder and bolt out of the gun.

I noticed that for a couple of the notches the bolt did not seat well. It took only the barest of filing to get it to work.

It seems like it's a game of .0001's of an inch

 

[45D]

I agree , with the hand driving the cylinder forward with increasing speed as per usual hammer manipulation, the slightly increased hand tension from the chimney angle on the hand spring is braking nothing of the cylinder inertia. Great theory though !
The much greater leverage of the bolt contact with the larger orbit of the cylinder circumference does brake the inertia.

Page 215 in your Kuhnhausen book will explain it to you. It concerns "spring pressure" suitable for the hand . . . " to prevent throw-by" .

So much for my "theory" . . .

Mike

 

[45D]

A line on the cylinder( not a groove) doesn’t mean it’s out if time.

That's exactly what it means or it's been mishandled by someone ignorant of proper S.A. handling.
The exception is the Ruger New Model Blackhawk. With a gate that unlocks the cylinder, it's only natural that it's going to have "double action" traits of a cylinder being turned with the bolt on it. That combined with an anemic hand spring setup is all it takes for beauty rings being the norm!!

Mike

 

[M. De Land]

Riiiiiight . . .

( loose yer Kuhnhausen book sir?)
Funny how sometimes he's the "King" and sometimes he doesn't know what he's talking about!!

Mike

That's exactly right when he gets it right and he usually does but when actual experience contradicts then one has to go with what their own senses dictate . No one knows it all but these folks are certainly worth listening to and then evaluating if it's the best or only way forward for ones self.
You don't seem to understand that there are methods and means different than what you have been taught that work just as well.

 

[45D]

That's exactly right when he gets it right and he usually does but when actual experience contradicts then one has to go with what their own senses dictate . No one knows it all but these folks are certainly worth listening to and then evaluating if it's the best or only way forward for ones self.
You don't seem to understand that there are methods and means different than what you have been taught that work just as well.

Of course sir, I'm sure you know better. In fact everybody knows better than the ones that actually "know".

Mike

 

[M. De Land]

Of course sir, I'm sure you know better. In fact everybody knows better than the ones that actually "know".

Mike

Well, I know whats better for me and the guns I'm working on at the time after considering what the "experts" have to say . The advantage I have is flexibility, ability and equipment to fabricate the parts and do the job any way I choose for the best outcome .

 

[Stantheman86]

I was looking at some old Colts for sale and lots of them had peened cylinders and drag marks from the bolt. Without mods like @45D does that action is the bare minimum of simplicity to make the cylinder index.

I've seen many older repros with the edges of the nipple recess cutout all peened up like they were slamming into the hammer nose, probably from clumsy handling, trying to spin the cylinder or the gun firing out of lockup

 

[45man]

No revolver, new or old should have super tight lockup. There must be a be a few thousandths play to allow the ball or bullet to steer the cylinder for good entry to the forcing cone. I have seen custom guns fit so tight the forcing cone wore on one side. Accuracy was non existent from day one.
I have one revolver approaching 200,000 rounds with no wear that can be measured. Years of winning competition with it taught me a lot about fit.