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wondering if patched round balls are still round after being driven down the barrel and then fired?
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lead round balls, are they really round?
- Thread starter deerstalkert
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It seems like it has been a long winter for you. Would keep a check on that mind and not let it wander too far. And would that be a stuck ball?
Phil Coffins
69 Cal.
Nope, the sudden start moves the back before the front moves. That lead has to go somewhere and that is to the sides. This is with round ball or bullets. Dr. Mann proved that even jacketed bullets do this. His book the “Bullets Flight” tells all about his experiments.
I have always believed there's some obturation, like a baseball being hit by a bat, but the topic is always debated in length here on the forum.
It's the basics of internal ballistics,,
It would have been a good topic for the show "Myth Busters" too try to solve.
It's the basics of internal ballistics,,
It would have been a good topic for the show "Myth Busters" too try to solve.
Doubt it ... to what degree though ... doubt it is much, as RBs aren't really aerodynamic to start with.
Lead is malleable or capable of being shaped or formed, e.g., by hammering or pressure, where a projectile may 'obturate' or swell up (for lack of better words) as a result of the compressive (and to a lesser degree rotational) forces associated with being fired down a gun barrel. But if the pressure is lower than the force needed to effect a'permanent change' or what is called plastic deformation (a change in the shape or size of an object due to an applied force) perhaps it may resume it's original state.
STARTED/SEATED - FWIW on another MZL forum there is a large test where someone drove patched RBs down into the bore using both a short starter in a tight bore and then thumb pressure in a coned muzzle. The test barrels all had a removable breech, plus they were able to remove any ball by hydraulic pressure at a low value, so as not to distort the ball. They didn't test 'fired' projectiles, but it was interesting to see they did observe obturaration of balls of 1 to 2 1/1000ths of an inch, all caused by the short starter! They used multiple balls and patch thicknesses, where the balls were vibrated round in a tumbler and measures to be 'round' and of consistent diameter prior to each test.
FIRED - I believe (but couldn't find it...) that somewhere online there is a picture of a roundball obturated when exiting the bore. IIRC the old Lyman BP Manual aso had the same black & white pictures.
For our BP uses, a great example of where obturation DOES happen is at the skirt or base of a Minie ball. Typically the Minie is sized 0.002" smaller than the lands and the skirt expands ito the grroves when fired.
Other than that, I'll grab a bag of popcorn and sit back and see what others have to offer ...
Lead is malleable or capable of being shaped or formed, e.g., by hammering or pressure, where a projectile may 'obturate' or swell up (for lack of better words) as a result of the compressive (and to a lesser degree rotational) forces associated with being fired down a gun barrel. But if the pressure is lower than the force needed to effect a'permanent change' or what is called plastic deformation (a change in the shape or size of an object due to an applied force) perhaps it may resume it's original state.
STARTED/SEATED - FWIW on another MZL forum there is a large test where someone drove patched RBs down into the bore using both a short starter in a tight bore and then thumb pressure in a coned muzzle. The test barrels all had a removable breech, plus they were able to remove any ball by hydraulic pressure at a low value, so as not to distort the ball. They didn't test 'fired' projectiles, but it was interesting to see they did observe obturaration of balls of 1 to 2 1/1000ths of an inch, all caused by the short starter! They used multiple balls and patch thicknesses, where the balls were vibrated round in a tumbler and measures to be 'round' and of consistent diameter prior to each test.
FIRED - I believe (but couldn't find it...) that somewhere online there is a picture of a roundball obturated when exiting the bore. IIRC the old Lyman BP Manual aso had the same black & white pictures.
For our BP uses, a great example of where obturation DOES happen is at the skirt or base of a Minie ball. Typically the Minie is sized 0.002" smaller than the lands and the skirt expands ito the grroves when fired.
Other than that, I'll grab a bag of popcorn and sit back and see what others have to offer ...
I doubt they are still perfectly round, if they ever really were. But what difference does it make?
Get's to be tricky ... if obturation is observed, how can one reasonable not presume it was the backstop that did it? I also think such a test would need the same caliber ball at various charges, e.g., 50, 70, to 90, etc., to be of value.
Now, we need an enterprising young man to measure the ball all around, mark the ball at the muzzle, send it home, shoot it straight up while next to a swimming pool, run for cover, observe the pool for splash, recover ball, measure the waist. prove that obturation was caused by firing, not the short starter.
Robby
Robby
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it has been a long winter, but the reality of my OP was just to see how opinions i received about what is a mostly useless bit of conjecture.it ranks right up there with "how many angles can square dance on the point of a needle!
actually the start of my ruminations on this was the .300 round ball i poked out after taking the breech out of my whatzit following a fail to fire.
it was flat on top (larger flat than a sprue) . it measures top to bottom where it rested on the powder at .2825
it measures across where it is inscribed with lands and grooves at .3005 in the grooves and the land incisions are .2895.
this ball was not fired so no obturation from that, just the effects of loading.
i am sure many of you will sleep much better tonight with the above information supplied!
have to go now, my snow man is melting and i need to give him some balls
a picture of my tiny ball.
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On the other hand they say if you shrunk the earth down to the size of a Q Ball it would be just as smooth. Think of that the next walk down the mountain.
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Just for fun I just tried running a patched ball through a barrel that doesn’t have a breech plug to see how much loading distorts the ball. The ball began at .395 plus or minus. After pushing the ball through, its largest diameter was .4067 or so.
so the ball is not round after loading. I suspect it is much less round upon firing.
so the ball is not round after loading. I suspect it is much less round upon firing.
Maybe I didn't understand physics when I was taught it, but I was taught that gas pushing against a surface conformed to that surface in an equal manner over the entire exposed surface....
Which would explain why there is little obturation of the sphere that is the patched, round ball, which has much less to overcome to get it moving, and why patched round ball shooters observed better accuracy when there was a visible sprue on that round ball, by loading the sprue upwards, facing the open muzzle, and thus taught as much...
And why there is much more obturation on a skirted or flat based conical compared to the round ball, those conicals have a very different surface impacted by the gas of the deflagrating powder, but also much more mass than a round ball so more inertia resisting that gas and thus those two factors, surface and mass, causing more pressure on the lead forcing it outwards to a much greater degree.
Here's a crude drawing of what I am writing about, patched round ball, skirted conical, flat based conical ...
LD
Which would explain why there is little obturation of the sphere that is the patched, round ball, which has much less to overcome to get it moving, and why patched round ball shooters observed better accuracy when there was a visible sprue on that round ball, by loading the sprue upwards, facing the open muzzle, and thus taught as much...
And why there is much more obturation on a skirted or flat based conical compared to the round ball, those conicals have a very different surface impacted by the gas of the deflagrating powder, but also much more mass than a round ball so more inertia resisting that gas and thus those two factors, surface and mass, causing more pressure on the lead forcing it outwards to a much greater degree.
Here's a crude drawing of what I am writing about, patched round ball, skirted conical, flat based conical ...
LD
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Dave you were a better student that you supposed. of course pressure is applied equally in all directions.
the curve ball in my question was the inclusion of being driven down the barrel and seated on the powder.
i found obturation on that tiny .300 rb after just the loading process. Darn thing wouldn't fire. so i popped the breech plug and pushed it out.
found the same as Bnewberry above. turned into a disk rather than a sphere. next is finding one in the snowman and checking it. i surmize it will mirror the loaded /recovered ball.
the curve ball in my question was the inclusion of being driven down the barrel and seated on the powder.
i found obturation on that tiny .300 rb after just the loading process. Darn thing wouldn't fire. so i popped the breech plug and pushed it out.
found the same as Bnewberry above. turned into a disk rather than a sphere. next is finding one in the snowman and checking it. i surmize it will mirror the loaded /recovered ball.
But that wouldn't work to prove anything.
It is a known measurement that free falling mass reaches a maximum velocity, H2O has it's own mass and resistance,,
To expand upon your given example; a human body can jump into water from a high point, right? And it will hit the water in a pointed position or a belly flop,,
All you have to do is "wipe-out" while water skiing once,, to know water is pretty darn hard thing to hit while mass is in motion.
,water has resistance that will cause deformation the ball.
The resistance caused by the impact negates the trial,,
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In my collection of dug Civil War bullets one stands out among the others. It's a fired .69 ball from a Buck and Ball load, imprints of the 3 buckshot are found on the ball, the ball also exhibits a smooth belt about it's circumference from the ball slightly being setback upon firing, this probably due to the additional mass of the 3 buck balls. JMHO
