Pietta cylinders slipping out of lockup

[Stantheman86]

Just an observation, about half of my Piettas have 1, or more chambers that "slip" out of lockup toward the leade side of the bolt

I've fired these guns 100's of times and haven't worried about it. It doesn't seem to matter if the guns have the cylinder that was in it from the factory.....one of these has, the factory cylinder, one has one I swapped in. A brand new Pietta 51 Navy I put a plain cylinder in locks up tight on all 6 chambers. A brand new
.44 Brasser with very few rounds through it and the factory cylinder, slips off on one chamber.

It doesn't seem to be a big deal , plus the nipple cutouts and hammer seem to be kind of a "backup" lockup point.

Only one revolver will slip when the hammer is cocked, the rest of them lockup tight at full cock.

I was just curious about this, I'm sure other people's Piettas do this and I can't have the only 4 in existence that slip the bolt like this.

 

[necchi]

Just an observation;
Your dissecting too closely for an expected modern tolerance situation.
The original firearms where made to shoot when the trigger was pulled.
Modern reproductions of originals are just that, not off the shelf improved versions of originals.
Now I have come to respect your knowledge and experience with the revolvers, what you share with us is priceless.
But isn't this issue simply the milling variables of individual cylinders within factory tolerance?

 

[45D]

The bolt is too wide for the notches. Pietta has somewhat of a history of "ill fitting" bolts in many of their SA's. A simple "dressing" of the right side (tall side) of the bolt on some 320 sandpaper ( on a flat surface . . . I use glass) until it fits the notches on all of the cylinders. A small amount of play is preferred over a solid hold off center.

I also notice no evidence of bolt head contact with the bottom of the notch, the above "dressing" may allow that to happen.

edit: I looked again and there may be some contact with the bottom of the notch. Just something to look for . . .

Mike

 

[Red Owl]

It looks like the bolts are popping up too soon. As stated, those percussion guns are pretty tough, the round ball sort of "straightens out" entering the forcing cone, etc. The mechanism is the same as the later Colt SSA Peacemaker so any book on that will work with the percussion. On a lot of replicas the bolt locks up before full cock but most folks are yanking back the hammer and never realize it. If it fires- that's the deal.

 

[Stantheman86]

Just an observation;
Your dissecting too closely for an expected modern tolerance situation.
The original firearms where made to shoot when the trigger was pulled.
Modern reproductions of originals are just that, not off the shelf improved versions of originals.
Now I have come to respect your knowledge and experience with the revolvers, what you share with us is priceless.
But isn't this issue simply the milling variables of individual cylinders within factory tolerance?

Thank You, I try to share my observations as I use the revolvers,

I own a good number of both brands , so I'm not bashing Pietta but none of my 10 Uberti's do this , from my London Navy with 1000s of rounds through it to my brand new Leech & Rigdon

It is a variance in machining, the bolt does not fully engage some of the stop notches due to slight variance in the stop notch width vs the bolt.

I just like to observe the various quirks of some of these revolvers and like 45D says there is an easy fix for it.

 

[Stantheman86]

The bolt is too wide for the notches. Pietta has somewhat of a history of "ill fitting" bolts in many of their SA's. A simple "dressing" of the right side (tall side) of the bolt on some 320 sandpaper ( on a flat surface . . . I use glass) until it fits the notches on all of the cylinders. A small amount of play is preferred over a solid hold off center.

I also notice no evidence of bolt head contact with the bottom of the notch, the above "dressing" may allow that to happen.

edit: I looked again and there may be some contact with the bottom of the notch. Just something to look for . . .

Mike

This looks like an excellent winter afternoon project

I did play around with some spare bolts I have, just to see if they "fit" the notches as I held the bolt in my hand and the 2 bolts were too big for the notches.

I would guess you would work slowly and carefully to dress the right side of the bolt until it slips fully into each notch

 

[Stantheman86]

It looks like the bolts are popping up too soon. As stated, those percussion guns are pretty tough, the round ball sort of "straightens out" entering the forcing cone, etc. The mechanism is the same as the later Colt SSA Peacemaker so any book on that will work with the percussion. On a lot of replicas the bolt locks up before full cock but most folks are yanking back the hammer and never realize it. If it fires- that's the deal.

All of the brand new Piettas I have are timed with later bolt drop than my earlier ones, the hammer will just lock into full cock as the bolt drops. I assume as a response to people yanking back on hammers cowboy style and throwing the weight of the gun forward against the hammer, which apparently is how you're supposed to cock a Colt

 

[Red Owl]

Here's some thoughts. There is the issue of poor tolerances and a different issue of rough machining. It has been my experience that most of the replicas today are made on machines with pretty good tolerances. What causes trouble is rough machining, a bur here or there that wasn't finished off correctly. Does every chamber not lock up or only one? I'd look for burs, etc. Maybe polish (without rounding off) some edges. The same applied to the racket and hand.

 

[William P Sepessy]

I believe 45D is correct about the bolt head. With any new percussion revolver I get the cylinder notches and bolt head are measured with a dial caliper. The older Piettas' were the worst offenders but I have caught a few Ubertis where one or two of the cylinder notches were slightly smaller than the others. This meant the bolt head would not completely drop in the notch.

 

[dylan84]

The bolt is too wide for the notches. Pietta has somewhat of a history of "ill fitting" bolts in many of their SA's. A simple "dressing" of the right side (tall side) of the bolt on some 320 sandpaper ( on a flat surface . . . I use glass) until it fits the notches on all of the cylinders. A small amount of play is preferred over a solid hold off center.

I also notice no evidence of bolt head contact with the bottom of the notch, the above "dressing" may allow that to happen.

edit: I looked again and there may be some contact with the bottom of the notch. Just something to look for . . .

Mike

Yep what he said!

 

[dylan84]

I had to correct both my 1858 and 1860. I was able to grind the bolt on the opposite side to get my alignment perfect on my 1858. Prior to that the chamber wasn't even lined up to the bore! Now to get my bolt timing better on the 1860.....

 

[springfield art]

This is more evidence of the quantity and quality of Percussion Advice people can get here.

 

[dylan84]

Just an observation, about half of my Piettas have 1, or more chambers that "slip" out of lockup toward the leade side of the bolt

View attachment 176459

View attachment 176460

View attachment 176461

View attachment 176462

I've fired these guns 100's of times and haven't worried about it. It doesn't seem to matter if the guns have the cylinder that was in it from the factory.....one of these has, the factory cylinder, one has one I swapped in. A brand new Pietta 51 Navy I put a plain cylinder in locks up tight on all 6 chambers. A brand new
.44 Brasser with very few rounds through it and the factory cylinder, slips off on one chamber.

It doesn't seem to be a big deal , plus the nipple cutouts and hammer seem to be kind of a "backup" lockup point.

Only one revolver will slip when the hammer is cocked, the rest of them lockup tight at full cock.

I was just curious about this, I'm sure other people's Piettas do this and I can't have the only 4 in existence that slip the bolt like this.

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

 

[dylan84]

I tried posting above a pretty good write up of what to do to fix these issues.

 

[M. De Land]

Just an observation, about half of my Piettas have 1, or more chambers that "slip" out of lockup toward the leade side of the bolt

View attachment 176459

View attachment 176460

View attachment 176461

View attachment 176462

I've fired these guns 100's of times and haven't worried about it. It doesn't seem to matter if the guns have the cylinder that was in it from the factory.....one of these has, the factory cylinder, one has one I swapped in. A brand new Pietta 51 Navy I put a plain cylinder in locks up tight on all 6 chambers. A brand new
.44 Brasser with very few rounds through it and the factory cylinder, slips off on one chamber.

It doesn't seem to be a big deal , plus the nipple cutouts and hammer seem to be kind of a "backup" lockup point.

Only one revolver will slip when the hammer is cocked, the rest of them lockup tight at full cock.

I was just curious about this, I'm sure other people's Piettas do this and I can't have the only 4 in existence that slip the bolt like this.

Before narrowing the bolt I would dress the top and corners of the bolt top itself. It looks like the top of the bolt is galling the cylinder where it drops indicating it needs smoothing.
If it fits into most of the cylinder notches but won't in others narrowing the bolt will only make it sloppy in the notches it will now drop into.
I also would brake the tops of all the notches with a diamond file or small triangular stone which may have some milling burrs.
Narrowing the bolt width would be my last item on the list of remedies as it will make it more loose in the frame window as well as the cylinder notches.

 

[45D]

Before narrowing the bolt I would dress the top and corners of the bolt top itself. It looks like the top of the bolt is galling the cylinder where it drops indicating it needs smoothing.
If it fits into most of the cylinder notches but won't in others narrowing the bolt will only make it sloppy in the notches it will now drop into.
I also would brake the tops of all the notches with a diamond file or small triangular stone which may have some milling burrs.
Narrowing the bolt width would be my last item on the list of remedies as it will make it more loose in the frame window as well as the cylinder notches.

Well actually, fitting instructions say to fit the bolt head to the "tightest" notch in the cylinder. It also says to level the right and left sides of the bolt (proper) to assure parallel sides (320 paper on a slab). The top leading edge ( tall side) of the bolt should be sharp and never rounded (broken just off horizontal with an edge to remove a wire edge).

An out of spec bolt window can be corrected with the installation of a " bolt block" which is one of the reasons that I install one in every S.A. I tune. All my revolvers have a better fit than the bolt window the revolver came with. Rounded edges on bolts introduce the user to what "throw-by" is.

Since the op is dealing with several cylinders ( of which I'm sure none were line bored to the revolver), my suggestion above would definitely be the easiest and best way resolve his problem. Even more so if he installed a bolt block.

Oh yeah, don't round any edge of the notches either . . .

If I'm wrong, so is Jim Martin and Jerry Kuhnhausen .

Mike

 

[Stantheman86]

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

 

[M. De Land]

Well actually, fitting instructions say to fit the bolt head to the "tightest" notch in the cylinder. It also says to level the right and left sides of the bolt (proper) to assure parallel sides (320 paper on a slab). The top leading edge ( tall side) of the bolt should be sharp and never rounded (broken just off horizontal with an edge to remove a wire edge).

An out of spec bolt window can be corrected with the installation of a " bolt block" which is one of the reasons that I install one in every S.A. I tune. All my revolvers have a better fit than the bolt window the revolver came with. Rounded edges on bolts introduce the user to what "throw-by" is.

Since the op is dealing with several cylinders ( of which I'm sure none were line bored to the revolver), my suggestion above would definitely be the easiest and best way resolve his problem. Even more so if he installed a bolt block.

Oh yeah, don't round any edge of the notches either . . .

If I'm wrong, so is Jim Martin and Jerry Kuhnhausen . I

Mike

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) .

 

[dylan84]

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 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.

 

[Johnny Tremain]

Before narrowing the bolt I would dress the top and corners of the bolt top itself. It looks like the top of the bolt is galling the cylinder where it drops indicating it needs smoothing.

Mine 1860 is doing the same thing. Mow I know how to make it stop. It just started scoring the blued cylinder.
Great info, great forum, thanks