patched rifle balls.

There is no doubting that a lead ball will obturate if given sufficient acceleration.

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How much is the question. So I picked some numbers out of the air to see; I tried to error on the moderate side of forces. Take a 170 grain round ball through a 42" barrel reaching 1700 fps in 0.002 second (That's probably too long) there's approximately 28000 G forces of acceleration. That figures to about 630 lbs of push on that ball, I wonder if that is enough to smoosh it a bit? If that ball launches in 1 millisecond you can double that number; 1260 lbs on the ball would be approximate 6400 psi of chamber pressure. Sounds about right. The ball is deformed a bit.

Thanks for the effort Fred, I have no idea how to calculate G force, we could talk G strings or G spots but, oh never mind. :haha:
I don't think we can calculate it quite that way since the initial acceleration would be very much greater than the average acceleration throughout the length of the barrel. However, the numbers you calculated do represent "a force to be reckoned with".

Coyote and Dan are right. Suggest you read Dr. Franklin Mann's book "the bullets flight" to understand obturation. cheers Paul

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Yup, they are plumb correct as regards bullets or columns of lead. But a ball does not fit that description at all, therefore different rules will apply. I've not read Mann, but unless it he writes about lead balls, then he would not be material to this discussion, IMO. Thanks for the reference though.

Joe, you gave a great description of how a lead bullet bumps up, but I think you err when you say lead balls and bullets are the same.

I'm not saying flat out that lead balls don't bump up. I'm just saying that the science of it is not applicable straight across the board and that so far we have not been able to adequately describe what actually takes place when a patched ball is subjected to the forces of a black powder charge going off.

How to test it? That's the question in my mind. What would a bumped up ball look like?

We also have a terminology problem here. To obturate means to plug a passageway. The projectile does not obturate. It may obturate the passageway but it does not itself "obturate". Dan got it right in his post.

In fact, we attempt to obturate the bore when we load a round ball. We probably don't completely obturated it but one goal of a tight load is to come as close as possible to obturating the bore. I have seen high speed photos showing burning gasses exiting the muzzle of a ml gun before the ball exits. How do we reconcile that with the idea that a patched ball that has been loaded tight enough to almost entirely obturate the bore still allows gasses to pass by it? Would it not be bumping up enough to prevent that from happening?

I think that most anyone would agreethat there is likely a small change in the shape of a lead ball, the question is is it enough to cause a noticable diiference in accuracy, some extensive controlled tests would be needed to shed light on this, anything else is just speculation with all the different combos and powder loads and variables all the players in this thread are faced with when making a determination/comparison, personaly for me it kind of goes past the "whether it matters" for my take on the sport as I try to approach shooting a ML it as one would have in the 18th century and the technology for measuring such was not really there, anyway, enjoy the heady stuff it is interesting at times.

marmotslayer said:

If you can't see the imprint of the rifling I guess you just don't know what you're looking at. I don't mean that to be derogatory but I think it is clear to see but you just don't understand what you are seeing since it isn't three dimensional.

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Well Joe, it comes across kinda derogatory without you even trying!

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T/C Hawken Flintlock with T/C .45cal x 32” x 1:66” RB barrel
90grns Goex 3F / Oxyoke wad / .018 pillow ticking / Hornady .440”

Heart shot six pointer at 50yds, broke a rib going in, flattened out on one side like an igloo
Through the heart, and stopped bugling the hide out at the far shoulder
Top ball is a new .440”, bottom is recovered ball, sitting on its flat side

And don't worry about not seeing patch weave or rifling marks on it anywhere...they're simply not there.

I have to agree with you as regards the value of this speculation as far as practical application goes. When we step to the line with pouch and horn over our shoulders, none of this makes any real difference. At that point, we have done our load testing and practice. Then, the proof is in the pudding.

Joe points out, and I agree 100%, that tight loads seem to be the most accurate. At least that's the way it is for me. It's also pointed out that some shooters get great results with loose fitting loads.

The only time I have observed good accuracy with a loose load was at close range with a .50 caliber rifle. The patches were all torn up and yet the balls were touching at 25 yards and very tight at 50 yards. Then I put it on paper at 100 yards and the small groups became 12" groups. :shocked2: So, I can see how a hunter or shooter could have used that load and gun for matches and hunting out to 50 yards with great success. If that gun was never tested beyond 50 yards one could conclude that loose loads that tear up patches shoot great!

We all have our own experiences and while we like to see the "truth" in our experiences, there are always other ways to view them.

And don't worry about not seeing patch weave or rifling marks on it anywhere...they're simply not there.

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At this point we have seen a number of photos posted and a number of actual observations posted that, taken by themselves, are quite contradictory. Some recovered balls show no patch or rifleing imprint, some show patch imprint but no rifling and some show neither.

The question would seem to be, "what else is going on here that we are not comprehending"

Hey, just cause I pose the question does not mean I have an answer! :haha:

Marmotslayer, you keep saying you see the marks of the fabric but you don't see any marks of rifling. The fabric marks ARE the marks of rifling, it is the lands of the barrel which have pressed the fabric into the surface of the ball.
The photos I posted are of balls just pushed through the bore. The only fabric marks are where the patched ball rode on the lands. That is why the marks are more distinct with thicker patching. So long as there is cloth between the steel and the lead I don't know how you could expect to see any other kind of mark but that of the cloth, which you admit you do see. If you don't call those "rifling marks" then I don't know what you imagine rifling marks should look like.
The fired and recovered ball posted by Stumpkiller shows fabric weave on the whole back side of the ball but very much deeper around the circumference where the ball rode on the lands. It is as plain to see as anything could possibly be.
I too could post a photo of a fired ball showing no rifling marks by simply turning those marks away from the camera.

"The question would seem to be, "what else is going on here that we are not comprehending"

I think it is simply the total lack of any constant in the equation, probably no one is talking of the same gun,loads,combo,powder and on and on yet all are being compared as though they were the same and should yeild the same results.

Agree...its a rare statement that can be made that will hold up across the board. I think a lot of it is just a lack of precision in how we humans communicate.

ie: for example, somebody will be shooting in very dry low humidity conditions and have to wipe after every shot or so if using natural lube 1000, and then make a sweeping across the board statement that "NL1000 is no good"...when its simply a case of an individual(s) assuming his experience is what everyone / everywhere experiences.

We can substitute almost any topic...for just about anything that's discussed somebody has had an experience and declares that experience as the all telling one, and then begins building rationale around it to justify / defend it...and very often, once we humans stake ourselves out on a position, we will then go to all sorts of lengths to save face on having taken that position...in spite of compelling evidence to the contrary.

roundball said:

...and very often, once we humans stake ourselves out on a position, we will then go to all sorts of lengths to save face on having taken that position...in spite of compelling evidence to the contrary.

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:grin: Or, as that other famous Russian, Leo Tolstoy, said, "I know that most men, including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining to colleagues, which they have proudly taught to others, and which they have woven, thread by thread, into the fabric of their lives."

Spence

And that is why Tolstoy"s books are soooo long. :haha:

Marmotslayer, you keep saying you see the marks of the fabric but you don't see any marks of rifling. The fabric marks ARE the marks of rifling, it is the lands of the barrel which have pressed the fabric into the surface of the ball.

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In that particular post I was not including the ones you pushed through. I do see what you are talking about. I was refering more to the state of the fired balls, including my own.

Roundball displayed a recovered ball which he could not find any weave marks on at all. Stumpkiller's was the opposite and showed weave and rifling. Mine shows only weave, but I must admit that I don't know if the actual contact portion of my ball is visible. It may be part of the flattened ball.

As far as obturation goes, I would expect to see not only the weave, but actual rifling marks on the ball as one would see with a modern bullet or a not so modern lead conical.

Way off Topic here, not trying to steal this thread, I think this is great and very informative post...

I have a simple question. Has anyone ever been on the recieving end of one of these roundballs?

Thanks for letting me ask.

God Bless

Lee

Virtually everyone who was shot with a rifled firearm prior to 1825 was shot with a roundball.
That's over 200 years of shootings.

marmotslayer said:

As far as obturation goes, I would expect to see not only the weave, but actual rifling marks on the ball as one would see with a modern bullet or a not so modern lead conical.

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Surely you jest. I have tried to politely explain why it is obviously impossible for a patched ball to be marked like bare naked lead but it now seems apparent that you are being deliberately obtuse.

Marmont buddy, your not getting a basic issue here.
The round ball is surrounded with a patch. It simply cannot be in direct contact with the rifling.
Where the ball contacts the rifling IS where the patch weave is left on the ball.

I beleive oburation happens, but this oburated ball does not remain in it's newly oburated shape after it leaves the bore (or during it's transit in the bore). That the shape of the ball actually osilates back too a more round shape, or it's previous round shape as the initail acceleration abates.
Newton's 3rd law; For every action there is an equal and opposite reaction.
That's why we don't "see" a recovered round ball in a new oburated shape.

Seems like a new law of physics is being born here:

A soft round lead ball changes shape due to acceleration...and then...soft lead, mind you..."springs back" to its original, or even another shape ?????????

So I guess the minnie-ball skirts flared to engage the rifling, then sprung back and disengaged?
Or Maxi-Hunters upset to best engage the rifling then spring back and disengage?

:shake:


I defer to my esteemed colleague's reference:

"...Or, as that other famous Russian, Leo Tolstoy, said, "I know that most men, including those at ease with problems of the greatest complexity, can seldom accept even the simplest and most obvious truth if it be such as would oblige them to admit the falsity of conclusions which they have delighted in explaining to colleagues, which they have proudly taught to others, and which they have woven, thread by thread, into the fabric of their lives..."
[/quote]

I'm in agreement with Roundball on that point, I can't see a pure lead ball once distorted springing back to a perfect sphere, lead has very little resilience, practically none.

"Seems like a new law of physics is being born here:'

I am conducting a test Roundball I just wacked a .570 ball with a hammer and am waiting for it to return to its original shape....nothing yet :idunno: