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What is the pressure disparity between BP and smokeless?
- Thread starter Pond James Pond
- Start date
45 Dragoon
New member
I see now why these posts keep coming around. Too many mouths, not enough ears.
Folks have been shooting normal factory ammo (not the cowboy stuff) in them from the beginning. I guess some could just admire conversions from a "safe" distance.
Mike
www.goonsgunworks.com
Folks have been shooting normal factory ammo (not the cowboy stuff) in them from the beginning. I guess some could just admire conversions from a "safe" distance.
Mike
www.goonsgunworks.com
I would like to see some actual pressure information, not "estimated". Bullet velocity is not a good way to determine pressure.
Agreed Jim.
that’s the topic I eluded to earlier in one of my posts . Just because your under 1000 or 110ftps , Doesn’t necessarily mean you have a lower pressure in the areas that count .
Same goes for size of round . Just because your shooting a smaller bore doesn’t mean there is less pressure . In fact it can be just the opposite.
I think however we do have to Not compare apples an Oranges as we concern ourselves with pressure . IE , while a 357 hot load will subject the cylinder in a revolver to the same pressures as a chambered round in an Auto , the revolver will not produce the same barrel pressures as that Auto .
The reasoning behind that is that pressure moves to the point of least resistance .
With a revolver , assuming everything is in proper condition , that point is the cylinder gap. Now that’s not to say that the barrel is not subject to pressure because it is . However that pressure is the result of what exceeds the amount escaping the cylinder . In other words the pressure builds faster then it can escape
Example ; vent on a flintlock .
So once again we are back to the design of the given application . Thus we are back to the question of can the design withstand the application ?
Well we know the cylinders on these conversions do when the advise of the manufactures are followed .
Which brings up the whole topic of powders , which again is apples and oranges and why I said ; it depends . You don’t just start loading powder in casings because what may produce a suitable load at 4.3 grains of A.S wouldn’t be suitable when using Unique .
that’s what we are doing when we try and compare BP to smokless as they react in most cases completely different
Black Powder is not slow burning . If a one were to lay a line of black powder next to a line of smokless . I don’t care if that line is 3ft or 2000ft , the line of black will go up near instantaneously . Where the line of smokless will sizzle , pop resulting in the fuse effect that you often see supposed BP do in the movies .
However , Contain that smokless powder. Give it some air space so that gases can build and you get a completely different result with a longer pressure curve that are often still building as the projectile is moving vs. BP which is often diminishing . Thus why , as you stated Explosive vs. propellant .
As far as the warping of an open top , if this were to happen Im of the opinion that one would see the signs rather quickly in the casings when using a mason type conversion, which I have also not seen with my 1851 .
Now what I have seen is the same issues that often plague the design even with BP applications . That’s issues with the quality of wedge pin . In my case I found the wedge pin to be rather soft . It had already been distorted and did not retain the barrel properly before I converted the piece .
Now I could be off here in my thinking but I have noticed that regardless of when im shooting in using the C&B cylinder or the Conversion, the pin loses its integrity on the side closest to the cylinder, thus giving me the impression that this is caused by the projectile entering the barrel . While I have found the same issue , with the same wedge while using the conversion , it doesn’t happen as quickly . However I was also in the beginning shooting .357 bullets in a larger bore . Thus in theory lessoning the effect of the bullet entering the barrel .
I have also seen other open top conversions that suffer from the same issue . Which has raised ,in my mind at least , as to if the real issue of the open top problems isn’t more of wedge pin failure vs. design incompatibility.
As I have stated a couple of times , I reload my .357 with 4.3 grains of AS which is the recommended load in their manual for lower so called cowboy loads .
Pressure also is subject to the bullet being used and since even my 125 gr heel bullets seem to be alittle on the lose side for my barrel , im seeing little concern about reaching to much pressure for my application with that powder .
It would be nice if Alliant would list pressure as part of their charts though
Now what I have seen is the same issues that often plague the design even with BP applications . That’s issues with the quality of wedge pin . In my case I found the wedge pin to be rather soft . It had already been distorted and did not retain the barrel properly before I converted the piece .
Now I could be off here in my thinking but I have noticed that regardless of when im shooting in using the C&B cylinder or the Conversion, the pin loses its integrity on the side closest to the cylinder, thus giving me the impression that this is caused by the projectile entering the barrel . While I have found the same issue , with the same wedge while using the conversion , it doesn’t happen as quickly . However I was also in the beginning shooting .357 bullets in a larger bore . Thus in theory lessoning the effect of the bullet entering the barrel .
I have also seen other open top conversions that suffer from the same issue . Which has raised ,in my mind at least , as to if the real issue of the open top problems isn’t more of wedge pin failure vs. design incompatibility.
As I have stated a couple of times , I reload my .357 with 4.3 grains of AS which is the recommended load in their manual for lower so called cowboy loads .
Pressure also is subject to the bullet being used and since even my 125 gr heel bullets seem to be alittle on the lose side for my barrel , im seeing little concern about reaching to much pressure for my application with that powder .
It would be nice if Alliant would list pressure as part of their charts though
45 Dragoon
New member
It has nothing to do with quality of the wedge. It has everything to do with the arbor.
Mike
www.goonsgunworks.com
Mike
www.goonsgunworks.com
45 Dragoon
New member
Your Uberti's arbor may be "holding up fine", but that doesn't fix the problem that it's too short. There is movement every time you fire it and the cylinder acts as a slide hammer. That is the problem.
My converted Dragoons have been holding a .0015 barrel/cylinder clearance and that is the final setting I made for them. They both easily hold a 2" group at 33 feet and typically put six shots in five holes (one is a little bigger than the rest!). The wedges are the original wedges and there is absolutely no "wear" to even speak of.
People pontificate about the mysterious problems that develop as they shoot there open tops (Ubertis or Piettas) and depending on the severity of the cylinder play (which is how fast problems will show) seem to marvel at what is happening to there beloved revolver!!
Countless times it has been talked about, written about, posted about, warned about . . . . then, throw a conversion cyl in the mix and OH MY GOD!! Do you think it's safe ?!!! I've heard of this and that and "you better not blah blah blah!!" Amazing!!
Guess what? Smokless cartridges put a different "vibe" when fired and your revolver will "age" rapidly unless attention is paid to the "normal" problems that come with modern open tops. The tolerances need to be ramped up significantly if you want it to last. It has nothing to do with off the shelf ammo, it has everything to do with the particular set up on your particular revolver. It seems to be the "can't see the forest for the trees" thing.
Mike
www.goonsgunworks.com
My converted Dragoons have been holding a .0015 barrel/cylinder clearance and that is the final setting I made for them. They both easily hold a 2" group at 33 feet and typically put six shots in five holes (one is a little bigger than the rest!). The wedges are the original wedges and there is absolutely no "wear" to even speak of.
People pontificate about the mysterious problems that develop as they shoot there open tops (Ubertis or Piettas) and depending on the severity of the cylinder play (which is how fast problems will show) seem to marvel at what is happening to there beloved revolver!!
Countless times it has been talked about, written about, posted about, warned about . . . . then, throw a conversion cyl in the mix and OH MY GOD!! Do you think it's safe ?!!! I've heard of this and that and "you better not blah blah blah!!" Amazing!!
Guess what? Smokless cartridges put a different "vibe" when fired and your revolver will "age" rapidly unless attention is paid to the "normal" problems that come with modern open tops. The tolerances need to be ramped up significantly if you want it to last. It has nothing to do with off the shelf ammo, it has everything to do with the particular set up on your particular revolver. It seems to be the "can't see the forest for the trees" thing.
Mike
www.goonsgunworks.com
45 Dragoon
New member
Captchee,
The arbor doesn't have to be stretched, loose, or anything else. The problem with all Uberti's is the arbor is too short (or the hole is too deep , take your pick!). If your conversion cyl is a thousandth or two shorter than your bp cyl, you have an even bigger problem. Close, tight tolerances are the answer. The job of the wedge is to just hold two assemblies together. The arbor against the barrel assy (bottomed out and tightly secured) conducts the shock from firing through the revolver as if it were one piece. ANY movement allowed by space at the end of the arbor will chew the wedge up, beat up the wedge key way and barrel contacts.
The arbor bottoming out is what constitutes your barrel/cylinder clearance, not the wedge.
In fact, I don't think there's a reason to take the tapped in wedge out until you're back from the range (or where ever) and cleaning the revolver.
Mike
www.goonsgunworks.com
The arbor doesn't have to be stretched, loose, or anything else. The problem with all Uberti's is the arbor is too short (or the hole is too deep , take your pick!). If your conversion cyl is a thousandth or two shorter than your bp cyl, you have an even bigger problem. Close, tight tolerances are the answer. The job of the wedge is to just hold two assemblies together. The arbor against the barrel assy (bottomed out and tightly secured) conducts the shock from firing through the revolver as if it were one piece. ANY movement allowed by space at the end of the arbor will chew the wedge up, beat up the wedge key way and barrel contacts.
The arbor bottoming out is what constitutes your barrel/cylinder clearance, not the wedge.
In fact, I don't think there's a reason to take the tapped in wedge out until you're back from the range (or where ever) and cleaning the revolver.
Mike
www.goonsgunworks.com
Yes I understand about the arbor and that issue was addressed during the conversion when it was shimmed . The problem im seeing is the wedge . To put it bluntly is as soft as an old Iver Johnson frame . When the accuracy starts to drop off , I will find the barrel to have slight play . Every single time the culprit has been the wedge beginning to distort on the cylinder side outer edges and the center width , matching the arbor on the loading lever side . IE the barrel is being forced forward away from the cylinder
A few taps to the wedge and she shoots fine for another 75-100 rounds .
However as I stated I experience this much quicker when using the C&B cylinder and less when using the conversion and smokless
Simply put the wedge will not hold a temper . Its crap steel . I simply need to make a new one .
But since I have pretty much went to just shooting cased rounds I have not made one yet .
A few taps to the wedge and she shoots fine for another 75-100 rounds .
However as I stated I experience this much quicker when using the C&B cylinder and less when using the conversion and smokless
Simply put the wedge will not hold a temper . Its crap steel . I simply need to make a new one .
But since I have pretty much went to just shooting cased rounds I have not made one yet .
45 Dragoon
New member
I would say there is still space there (end of arbor). If you tap the wedge in will the barrel bind the cylinder? The wedge can't get "beat up" if there isn't room for movement.
I shoot pretty warm loads (same .45s are shot in all my S.A.s) and my '60 (the smallest of the lot) has no problems with the load.
In the old days, when drilling through rock by hand, one man held the bit while the other man struck it with a sledge hammer. As long as the bit is held tight, no problem (the force travels to the rock), if held loose it would hurt like hell because the force could travel elsewhere.
Same with the open top set up.
My wedges are held in under tension by the wedge screw (I re-mount the spring for this) and it works flawlessly. Of course, all mine are conversions and shot with smokless loads so I don't take them down very often. I don't do that with customers guns unless asked to.
Mike
www.goonsgunworks.com
I shoot pretty warm loads (same .45s are shot in all my S.A.s) and my '60 (the smallest of the lot) has no problems with the load.
In the old days, when drilling through rock by hand, one man held the bit while the other man struck it with a sledge hammer. As long as the bit is held tight, no problem (the force travels to the rock), if held loose it would hurt like hell because the force could travel elsewhere.
Same with the open top set up.
My wedges are held in under tension by the wedge screw (I re-mount the spring for this) and it works flawlessly. Of course, all mine are conversions and shot with smokless loads so I don't take them down very often. I don't do that with customers guns unless asked to.
Mike
www.goonsgunworks.com
even a tight pin or wedge will compress and eventually shear if the metal is to soft
i dont believe there to be any play Dragoon . i inlet it and get good transfer from the end of the arbor onto the shim .
i think whats happening is the wedge is crushing just enough . The wedge shows this in the center front and then on the back in 2 places which match the walls . So its not the arbor being pushed in , more like the barrel being pushed forwards .
But its no concern , ill make a new one soon enough
i dont believe there to be any play Dragoon . i inlet it and get good transfer from the end of the arbor onto the shim .
i think whats happening is the wedge is crushing just enough . The wedge shows this in the center front and then on the back in 2 places which match the walls . So its not the arbor being pushed in , more like the barrel being pushed forwards .
But its no concern , ill make a new one soon enough
45 Dragoon
New member
You didn't say if you can bind the cylinder by pushing the wedge in "too far". Normally, if a wedge can be deformed, it's because there is room to allow it. Of course, the contact points you point out are the same on all open tops and the deformation is the same. Sonic vibrations can be very destructive and a firm, solid connection is the prevention.
If you load off the revolver and use hard lead combined with much oversized chambers for the bore and or misalignment of the chamber/bore, that might be a possibility (assuming the arbor is correct). You may check for that condition. Resolving this problem would be a good lesson for folks reading this thread.
Mike
www.goonsgunworks.com
If you load off the revolver and use hard lead combined with much oversized chambers for the bore and or misalignment of the chamber/bore, that might be a possibility (assuming the arbor is correct). You may check for that condition. Resolving this problem would be a good lesson for folks reading this thread.
Mike
www.goonsgunworks.com