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Pietta cylinders slipping out of lockup

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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.
That is interesting you say that as I accidentally ground my bolt on my NMA too narrow. I was prepared to order a new one but it shoots and cycles great now! It has a little rotational shake but doesn't seem to matter much. The chamber to bore alignment is much better now also. Before it was off to one side.
 
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.
Well, line bored custom and semi custom made guns (not talking about tuned up guns ) will have a lock up with virtually no lateral movement and they will pretty much stay that way. These guns are capable of minute of angle ( one inch at 100 yards) over a bench with all the chambers used in the same group.
There always has to be some clearance or they would not lock at all but perfect alignment and minimal clearance promotes accuracy.
I suspect but have not mic'd out that some of Linebaughs or Bowen's guns have a tapered bolt, window and notch arrangement that keep things centered and wearing tight. Just a hunch mind you that may be wrong.
 
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Well, line bored custom and semi custom made guns (not talking about tuned up guns ) will have a lock up with virtually no lateral movement and they will pretty much stay that way. These guns are capable of minute of angle ( one inch at 100 yards) over a bench with all the chambers used in the same group.
There always has to be some clearance or they would not lock at all but perfect alignment and minimal clearance promotes accuracy.
I suspect but have not mic'd out that some of Linebaughs or Bowen's guns have a tapered bolt, window and notch arrangement that keep things centered and wearing tight. Just a hunch mind you that may be wrong.
I admit some makers of custom revolvers do get it right but we are talking factory guns that need some cylinder play. I will not mention the maker of the one I mentioned but the price was steep. It seems it was not line bored as the original cylinder was used, just all play removed to the detriment of accuracy.
 
I admit some makers of custom revolvers do get it right but we are talking factory guns that need some cylinder play. I will not mention the maker of the one I mentioned but the price was steep. It seems it was not line bored as the original cylinder was used, just all play removed to the detriment of accuracy.
Did it spit lead? It's important to keep the inside corners of both forcing cone and chamber mouths a sharp profile with a slight braking to remove burrs, to discourage gas cutting.
Have you ever noticed any top strap cutting from your solid frame guns with black powder use ? It's common in magnum revolvers with lots of rounds down spout !
 
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No, it did not spit any lead, just wore the side out of the forcing cone.
let's discuss line boring for a second. First the boring tool is smaller then land diameter to fit down the bore. A starting hole is made but then all further work is done with the cylinder out of the gun. The throats still have to be machined to around .001 over groove and chambers must be reamed, all done in a fixture. Since most is done out of gun, just how much does line boring keep all in line?
Top strap cutting only reared it's head with the .357 super mag cartridge. Gas escape pressures were too great. This only progressed to a point and stopped without any further cutting to make it dangerous.
 
No, it did not spit any lead, just wore the side out of the forcing cone.
let's discuss line boring for a second. First the boring tool is smaller then land diameter to fit down the bore. A starting hole is made but then all further work is done with the cylinder out of the gun. The throats still have to be machined to around .001 over groove and chambers must be reamed, all done in a fixture. Since most is done out of gun, just how much does line boring keep all in line?
Top strap cutting only reared it's head with the .357 super mag cartridge. Gas escape pressures were too great. This only progressed to a point and stopped without any further cutting to make it dangerous.
The route I took with my 58 Pietta was to remove the barrel and made a reaming fixture that fit the major thread diameter of the receiver/solid frame, barrel hole threads, with a very tight interference fit ( no wiggle). This fixture guided the reamer into the existing chambers with the cylinder left in the frame and held by the bolt in the gun. Light cutting was the order of the day and metal removal in each chamber was being guided by the lock up of each chamber in the existing gun. I was getting a clean thin cut of fresh steel from all sides of each chamber so knew the reamer was well centered. A check with a plug gauge that would just fit down bore and into each chamber after the barrel was reinstalled confirmed excellent alignment.
This is not the same as line boring with a new cylinder billet which I believe is generally accomplished through the frame with a boring fixture, not through the barrel bore. Once the hole is bored in perfect alignment with the guns frame hole, it is easy to keep alignment when removed to a mill or drill press and mill vice with x-Y cross axis travel and reamed to final dimension as each chamber is positioned with a plug gauge, the gauge removed and the reamer installed to make the cut . This insures perfect alignment and uniform depth with the pre bored hole located by the actual guns frame and bolt fit.
See my thread on chamber reaming in the 60 Centeuar rebuild . There is a section on how chambers are located out of the gun and precision reamed.
Line boring in and open frame gun through the barrel would not be as precise as in a sold frame design because the arbor does not hold the barrel in as good and solid alignment as does a frame. The chambers bore alignment is not as consistently coaxial with a barrels bore as in solid frame guns.
 
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No, it did not spit any lead, just wore the side out of the forcing cone.
let's discuss line boring for a second. First the boring tool is smaller then land diameter to fit down the bore. A starting hole is made but then all further work is done with the cylinder out of the gun. The throats still have to be machined to around .001 over groove and chambers must be reamed, all done in a fixture. Since most is done out of gun, just how much does line boring keep all in line?
Top strap cutting only reared it's head with the .357 super mag cartridge. Gas escape pressures were too great. This only progressed to a point and stopped without any further cutting to make it dangerous.
A point I alluded to earlier is shooting a group with all the cylinders chambers as opposed to what is occasionally done in that a person will find one or more chambers have better accuracy than the rest (common with factory guns) and shoot a group using only the most accurate ones. This is because of inconsistent barrel/chamber alignment or depth in most instances. A loose bolt/notch/window fit that allows increased random lock up positioning would not be as accurate as tight consistent fit that launches the projectile be it ball or bullet aligned with barrel bore, the same way each time.
 
Some great comments there fellas and I agree. I have been a long range revolver shooter since my first .44 Blackhawk when I was 18, shooting over 400 yards at rocks on a RR bank. Here is a drop test of 5 shots from my BFR in .500 JRH at 200 yards, Custom shop gun.
 

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I know, modern gun but all applies to BP as well. One thing I found with some BP revolvers is the twist rates are wrong. Many too fast for a RB.
 
I know, modern gun but all applies to BP as well. One thing I found with some BP revolvers is the twist rates are wrong. Many too fast for a RB.

Yeah but just right for 45C / 45acp !!!
Lol

Mike
 
Some great comments there fellas and I agree. I have been a long range revolver shooter since my first .44 Blackhawk when I was 18, shooting over 400 yards at rocks on a RR bank. Here is a drop test of 5 shots from my BFR in .500 JRH at 200 yards, Custom shop gun.
Many won't do that at 25 yards from a Ransom Rest let alone 200 yards from sand bags I presume ! Sensational shooting indeed! Was this using all the chambers ?
 
The problem is they shoot way high with them there unmentionable loads! lol

Well, I clean up my rear sight for daylight on both sides but mine shoot pretty close to the sights.
Here's 10 shots at 10 yards with the acp off hand.
20221117_182540.jpg


Mike
 
Nice! Do you add a taller front sight too or just mess with the hammer notch?

Just the hammer notch. It's probably a combination of my parts choice combined with my particular way of arbor correction. The cylinders for my '60s are Pietta length ( longer) than Uberti cylinders. That allows for a slightly thicker spacer which means a slightly "more or less" level barrel than using an Uberti cyl. Of course, the Dragoons /Walkers are all the same " Uberti " cylinders. But they shoot close as well.

Mike
 
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