Do you believe that lead boolits actually obturate (swell up) when fired? Yes or No

[lwknight]

How can a boolit not obturate with 50,000 pounds pressure applied to the base?

[chief3]

Wish I had the pics I saw years ago but I can't even remember where they were published. They had a white background with referance lines that showed the boolit was larger than the bore. Don't know how they did it but it looked good. This was about 45 yrs ago.

[Russel Nash]

Last I checked, a baseball and a golfball was NOT made up of one singular homogeneous mixture.

There are several different materials involved in the construction of both.

slight thread drift ahead.... I remember hearing that one season of major league baseball had more homeruns because the internals of the ball were wound more tightly with string. This was back when the baseballs were wound by hand. The baseballs were made overseas, and the people were happier because the weather was better and the harvest season was more bountiful.

I guess they have computer controlled machines that do the winding now:

http://www.enotes.com/how-products-e...pedia/baseball

[Russel Nash]

lwknight wrote:

How can a boolit not obturate with 50,000 pounds pressure applied to the base?

Conversely, if a boolit were to obturate too much then your gun would go KABOOM!

Right?

[felix]

Right on both accounts exhibited above. ... felix

[jbunny]

my bud has 4 sweedish remmington rolling block rifles 50-70. 3 of those have
the hex metford rifleing, he shoots mild loads 31 gr of 3031 behind a 400 gr
soft lead boolit. the boolits are cast round. we recovered a whole pile of boolits
this spring after the snow melted. the boolits were all hex shaped. u be the judge.
jb

[Greg in Malad]

Ok fellers,
I have fired .450 diameter conicals in a .458 groove diameter muzzleloader barrel. The bullets would drop to the bottom of the barrel by their own weight. When shot into wet newspaper they had rifling engraved from nose to base.

[lwknight]

well that all stopped me from going into the use of 428 boolits in my 430 sized 44-40 bbl.
__________________

The boolit has to be big enough to seal the barrel first. Then all that pressure on the base will flatten most of the boolit to expand it to the barrel size. Jacjeted bullet bases do not expand on inpact with water, Full metal jacketed bullets do not expand on anything short of cold steel impact. The only way to prove or disprove would be to use the same bullet in 2 dfferent sized barrels being that one is larger than the starting size of the bullet.

When the recovered slugs are measured, if shot at high pressure loads, the base will be fully obturated to the bore/grooves. It may not work with cast boolits that are undersized because the gases will cut away the lead as it passes around the boolit. Resulting in leading the barrel.

We know that boolits that are too hard for a mild load can lead up a bore because they don't bump up to size.

[Frozone]

Last I checked, a baseball and a golfball was NOT made up of one singular homogeneous mixture.

It doesn't matter. take a piece of steel bar stock and use it as a bat, swing it at an airborne ball of lead and see what it looks like. It'll be distorted at the impact point and all that was in front was air. And just to head off a bit of argument, it wouldn't matter if you used a gas, a liquid, or a solid you'd get the same effect. Only the degree of displacement will vary. If this wasn't true you'd have a hard time cutting steel with a water jet.

[runfiverun]

We know that boolits that are too hard for a mild load can lead up a bore because they don't bump up to size.

xactly,but the softer ones i do use will, the larger ones won't chamber.
i have to size these down from 430 to 428 however i have exactly zero leading.
....now.......
but i have to use a stout load of 2400 to get there.
i don't like to bump up any type of lead in a revolver,rifle what have you but you do what it takes to make things work correctly.
i have often wondered why fmj's in rifle and pistol variety have a dished out base?????
hmmm.
the ones i have recovered after being fired that didn't start that way sure ended up with one. lead compresses under pressure,if it didn't we wouldn't be able to swage boolits or extrude pipe while the lead is cold.

[Deliverator]

Springfield wrote:



I am assuming that you are putting the cast boolit like on a heavy duty steel table or an anvil or out on a concrete sidewalk. And then you are whacking it with a hammer.

If so, then that really isn't an apples to apples comparison in my opinion

Springfield wrote:



I couldn't get all that to fit on the thread's subject line.

Here is a better one, take a baseball bat, then toss a piece of lead into the air and strike it with the bat. Then look at the piece of lead and see how it now has a distinct imprint of a baseball bat.

Same basic principle, a force is being exerted suddenly against a soft solid causing a distortion of the material. When this happens in a barrel there is something there to stop it from turning into a flat piece of metal. A force is a force is a force is a force and so on and so forth. It is the EXACT same principle as what happens when a flying bullet strikes a solid steel plate. Its all the same. And if you even TRY to deny that, you are just denying it to get an argument.

[Russel Nash]

I never said that lead was NOT malleable.

I'm still saying that my own personal jury is out on this obturation concept.

[Russel Nash]

runfiverun wrote:

lead compresses under pressure

for the sake and sanity of scientific discussion let's NOT use the word compress when it comes to talking about a solid like a lead boolit.

[Russel Nash]

Deliverator wrote:

It is the EXACT same principle as what happens when a flying bullet strikes a solid steel plate.

No, it is not.

A lead boolit contained along its length by a steel bore or barrel has no where else to expand to. It can only travel out the bore, in one direction.

A flying bullet striking a steel plate is not really contained by anything.

[Russel Nash]

runfiverun wrote:

the ones i have recovered after being fired that didn't start that way sure ended up with one.

In what medium did you recover these bullets in/from?

[Bullshop]

Why are you tossing out the obvious with muzzle loaders? A gun barrel works the same no matter how it is loaded.
Anyway you didn't pay any attention to what I said about the jacketed .451" Hornady 300gn XTP bullet being fired in the muzzle loader. It was not even close to the hollow base mini you mentioned then wrote off as what a muzzle loader shoots.
It would not have made any difference weather it was fired in a muzzle loader or a cartridge rifle, it would have done the same thing.
I am willing to bet if you took the same bullet and charged a 45/70 case to the same pressure as the ML the same .451" Hornady bullet will be fully engraved by a .458 groove barrel.
The problem you have is you are putting too much faith it your higher education and keeping a very closed mind. I think the issue is that you are stuck on a word, compressed. Compressed is the wrong word here so technically you are right the bullet mass is not compressing it is swagging. It is becoming fluid under pressure and flowing to the areas of least resistance, the grooves.
If you have noticed a recovered bullet or boolit after firing is not the same shape that it was before firing even if there is no expanding from impact.
I remember reading something from Dr. Mann where he was shooting base band bullets.
In this case he was shooting .257" diameter jacketed bullets with a .264" gas check crimped on its base.
He was firing them in a .264 caliber rifle possibly a 256 Newton. His idea was to achieve ultra high velocity by reducing drag in the barrel by using this base band bullet as he called it. Most of the length of the bullet was riding the lands ( bore ride) and only the gas check was full diameter for caliber.
What he found was that the recovered bullets were fully engraved for the length of the bullet. Not compressing but swagging up to caliber, same as they do in a die under pressure, same as all factory lead core jacketed bullets.
Your obviously a smart fellow so why don't you get this?
BIC/BS

[Deliverator]

Deliverator wrote:



No, it is not.

A lead boolit contained along its length by a steel bore or barrel has no where else to expand to. It can only travel out the bore, in one direction.

A flying bullet striking a steel plate is not really contained by anything.

Actually it will expand in every direction until it interacts with something stronger than the force of its expansion, thus being contained. Same thing with when it strikes a steel plate. The steel plate is stronger than all other directions thus why it expands outward until its energy is expended.

I thought you were supposed to be some kind of scientists that knows stuff...

[Russel Nash]

Frozone wrote:

..... water jet.

Some...not all "water jets" are also actually using an abrasive like garnet to cut whatever material.

http://science.howstuffworks.com/question553.htm

That is also 55,000 psi through an orifice that is about 10 thou to 15 thou in diameter

For a bullet, we are talking about...oh...I dunno...24,000 psi over a 356 thou diameter circular surface.

[Russel Nash]

Deliverator wrote:

thought you were supposed to be some kind of scientists that knows stuff...

why so snarky?

And, NO, I never did say I was a scientist.

[Russel Nash]

Bullshop wrote:

What he found was that the recovered bullets were fully engraved for the length of the bullet. Not compressing but swagging up to caliber, same as they do in a die under pressure, same as all factory lead core jacketed bullets.

Just curious then...what were the lengths of the boolits, the pro-jo's before they were shot vs. the lengths of the boolits after they were shot/recovered?