patched rifle balls.

[CoyoteJoe]

The subject came up when someone mentioned that they had never seen rifling marks on recovered balls, whereas I have always seen them. So I decided to conduct a little test by just pushing patched balls through an 8" cut off rifle barrel. I'm not sure of the make of barrel, probably Green Mountain. It has 8 lands with grooves about .012" deep and somewhat wider than the lands. The first photo is of the bore.

I used Hornady swaged .490" balls with three different types and thicknesses of patching, all lubed lightly with deer tallow just to ease ramming them through the bore.
Here I might explain my method of measuring patch cloth thickness. I agree with Dutch Shultz that it is the compressed thickness which matters and some cloth compresses very much more easily than others. But after ruining a good micrometer by cranking it down hard as Dutch recommends I decided that was enough of that method. I now use my digital caliper, pressing the slide against the cloth just tightly enough so that when I release the pressure it will spring back one or two thousandths. I then record the "spring back" measurement as the thickness of that cloth. Lightly compressed with no damage to the instrument.
The first on the left is pillow ticking which by my method measures .016". This took only a light rap on the short starter, one could shoot this load all day without bruising the hand. The photo shows faint marks from the rifling, more visible in close examination than in the photo.
Next is cotton canvas which measures .027" and required several hard raps on the starter before cutting the patch. This is the kind of load I prefer for accuracy and shows distinct engraving of the lands.
Last is with .024" linen canvas. Linen does not compress nearly so much as cotton and even though this is thinner than the cotton canvas it definitely required a rawhide mallet to drive the ball starter enough to cut the patch and the nose of the ball was deformed by the concave tip of the ball starter. Here we see marks of the fabric pressed into the ball not only by the lands but even faint marks at the grooves.

Conclusions? Even a rather easy to load combination will show at least faint rifling marks on a soft lead ball.
Does obturation play a role? I think it does since recovered fired balls seem to show more distinct rifling marks than do the balls just rammed through a section of barrel. Also, some people report good accuracy with loads they can thumb start. I have to think their balls do obturate, else wise they would group like a smoothbore. Personally I've always found tighter loads to produce tighter groups.

 

[tg]

Is the from difference obturation or heat?
Someone needs to shoot some balls a long distance into a sand trap or other soft catch method to measure them, that is about the only way one can tell and then the debate would just be whether it helps accuracy noticably, I think Rounball did something along this line if I recall

 

[necchi]

I'm with ya Joe, and Thanks for the excellant photos.
I've known for years thet patch fabric should at least "impart" an impression to the ball for a proper load. Something needs to make the ball spin. Those that don't see any marks in my opinion just aren't looking for them or don't want to see them and be found wrong.

Dutch does explain to have your hands/fingers on the shank of the micrometer and not the handle when getting a compressed fabric measurement but it's really a relative thing. As long as the same person is making the measurement with the same technique to all fabric, the measurement only pertains to him and the fabric variables.
Then it's up to the individual to experiment with his own loading/lubrication technique to determine what the best fabric is.
It always drives me nut's when I see the "What color Pillow ticking is Best?" topics when in fact 3 bolts from 3 different stores could all have different characteristics even though they are indeed the same color, Heck, 2 different bolts from the same store can be different.

 

[CoyoteJoe]

That's a fact, cloth is not made with precision in mind. My buddy Greenmountainboy buys his patch cloth by the bolt so he doesn't have to worry about it being different or unavailable the next time he goes to the store. If I buy two yards it looks like a life time supply to me but he shoots as much as I used to 40 years ago. :haha:
You probably also noticed the patches cut at the muzzle are much smaller than the packaged precuts, so you get many more patches from a yard of cloth.
Uuuh, you may also have noticed that my patch knife needs sharpening. :redface:

 

[roundball]

I've known for years thet patch fabric should at least "impart" an impression to the ball for a proper load.

Which coyote joe post are you referring to? First he said he didn't 'think' balls needed to obdurate for accuracy...then he says he 'thinks' they do.

To help you better understand:
As long as a patch grips a ball snugly enough to transfer rotation, the remaining patch material that's wedged down into the grooves is what provide steerage from the rifling twist...not from the lead having to engage with the lands like a .30-06 bullet engages with its rifling.

Those that don't see any marks in my opinion just aren't looking for them or don't want to see them and be found wrong.

That's just an absurd statement...you should know better than that when dealing with adults.

I always use .010" under bore size balls and at least .018" patches...as an example:
GM .610" bore x .012” square cut grooves by Ed Rayl
100grns Goex
.018" pillow ticking
Dead center through my POA...the heart of an 8 point buck at 55 yards.
Not a patch weave or rifling groove mark on it.

Every other ball I’ve recovered looks the same, and I get single ragged holes at 50 yards all day long without any weave marks on balls or having marks on them from engaging the rifling at all.

Balls ride on the lands like a train rides on rails...the patch does it all providing steerage from being wedged into the grooves and gripping the ball snugly... .40/.45/.50/.54/.58/.62 calibers, doesn’t matter.

 

[CoyoteJoe]

Actually Roundball what I said in that post on the smoothbore forum was this.

"If obturation of a round ball is to occur at all it would be most noticeable in large calibers with heavy powder charges. But it still would not take the form of a noticeably flattened rear but just a shortening of the front to rear dimension and a swelling of the side to side dimension."

I still don't profess to know for certain if obturation does occur with patched balls but it is my impression that balls fired and recovered have shown more pronounced rifling marks than I got by just pushing a ball through a section of barrel. That, plus the fact that some people claim good accuracy with very loose loads, leads me to believe obturation may be a factor but I make no claim to knowing for certain.
Also, under the topic "max kill distance" on page 4, Stumpkiller displays a photo of a ball recovered from a deer which shows very distinct marks from the fabric pressed in by the lands. It doesn't take much pressure to imprint marks on pure lead.

 

[tg]

I think that with all the talk of smoothbores and rifles and variable combos and powder loads and tighness, hardness of different lead we are likely talking apples and oranges by now.

 

[necchi]

I was refering only to this post and those photo's.
Plain enough to see for me.
And I hope you have a wonderfull evening Bill, :grin:

But the rest of it is just kinda, :yakyak:

 

[Semisane]

Here's the only ball I've ever recovered from a deer. It's .535 cast from pure soft lead in a Lee mold and shot from a Great Plains flintlock over 85 grains GOEX FFFg with a .016 patch lubed with olive oil. I can detect no fabric weave or rifling marks on it. I believe the indentation/crease is from hitting the rib.

The buck weighed 168 lbs. It was a frontal shot that turned out to be 88 yards measured with a laser range finder. The ball entered the chest cavity through the brisket cartilage, destroyed part of the right lung, exited the chest cavity between the second and third rib while clipping the third rib a little and cutting a "half moon" from the side of it. It stopped under the skin behind the shoulder.

 

[Stumpkiller]

Here's the only ball I ever recovered in a deer. Not only rifling marks but the lubed cotton pressed the pattern into the lead. Almost no expansion.

Went the full length of the deer from a frontal at 10 yards and lodged under the skin behind the femur. Deer dropped without moving from the spot.

 

[caseyb]

great photo, I have also recovered .490 round balls and have seen the thumbprint pattern of an .18 patch and engraved rifeling as well.also barrels are like people they are all different and some will be snuger than others and show more of the impression with some load combos than others. :thumbsup:

 

[Tom Compton]

The few roundballs I have recovered from deer could not show fabric or rifling marks as the lead flattened to such a extent that there was no waist to view. Ball .005 under nominal bore and .015 patch in Douglas 1/66 barrels.

TC

 

[longcruise]

Here we see marks of the fabric pressed into the ball not only by the lands but even faint marks at the grooves.

Joe, I see the print of the patch but I can't see the rifling marks. Not saying they aren't there, I just can't see them.

Here are two pics of the only ball I've ever recovered from an animal. There is a front and back pic and one of them has a .535 ball alongside for size comparison. FWIW, the widest point on the fired ball measured .74. The ball was .470 thick.

.535 RB.
.024 canvas patch lubed with dry patch NAPA system.
110 grains of ff goex.
hit a full grown cow elk broadside at about 45 yards.
Struck a rib going in and went between the ribs on the far side.
Muzzle velocity would have been around 1800 fps.

So, as you can see, the imprint of the patch is perfectly clear on the back side. I can't find any rifling marks. This was a very tight load in my rifle! Since the very bottom of the ball has patch imprint, I conclude that the imprint was put there by the pressure of the shot fired. Also note that some of the "back" of the ball would have been at least partially the side of the ball before it impacted the elk and flattened out.

Did your balls have a patch imprint on the bottom or just the sides? :redface:

Not posting this as an agreement or disagreement. Just added info.

On the topic of obturation, I'm on the "no obturation" side of the fence. My reasoning is this; The ball is round, the pressure is applied evenly to every point of the bottom half of the ball. It should tend to equalize the pressure on the ball, be it from the weight of the front half of the ball resisting motion or from the pressure of the expanding gasses of the powder burn.

Here is my drawing of what I think happens;

 

[tg]

I think physics might support that theory myself

 

[paulvallandigham]

The Softest "catch method" is Water. You can imitate sufficiently the Upset needed to show fabric weaves and lands on a PRB by using 40-50 grains of FFFg and shooting the round ball into a barrel of water. Yes, it does splash. But, you will get the lands and grooves marked on the balls, along with the weave pattern of your patching, too. At the slower velocities, water will only flatten the nose of the ball a little, leaving the sides, which contacted the lands through the patch, and the rear of the RB intact.

Since the PRB impacts the water Outside the barrel, and fabric markings, and lands shown on the side of the ball have to have been made INSIDE the barrel. :hmm: :thumbsup:

 

[CoyoteJoe]

The photo's I posted were of balls just pushed through a section of barrel so there was no pressure on the bottom of the ball, thus no imprint of fabric. 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. If you had those balls in hand it would be obvious, the tightest load even push some lead from the lands over into the adjacent grooves.
I certainly agree that the pressure of powder gas is equal all over the rear surface of the ball, but that has nothing to do with obturation. It is the inertia of the ball, an object at rest tends to remain at rest, resisting the force of powder gas trying to accelerate the ball. Just as when you floor the accelerator of your auto and you feel your body pressed back into the seat. The seat is accelerating and your body is trying to remain stationary. Now imagine if you were in a rocket sled capable of accelerating from a standing start to 1800 fps, 1227 mph, in just three feet of travel! I don't know how to calculate the G forces but they would be incredible and your body would be totally liquefied.
We all know obturation is vital in long range rifles firing conical bullets. They load a bore size bullet which is a slip bit down the bore and depend entirely on obturation to fill the grooves when that bullet is fired. In that case it is a delicate balance of powder charge, powder granulation and bullet alloy to obtain the proper obturation. But those are long, heavy bullets which have great inertia to resist the force of acceleration. Round balls are the shortest and lightest form of projectile and while the same forces are at work the inertia of a ball is very much less than that of a conical bullet. Still, the G forces are incredible and pure lead is quite soft.
The more I think about this the more I come to agree with Dutch Schultz who claimed that relativly heavy powder charges were necessary for best accuracy with patched balls due to the need for obturation.

 

[Dphar]

Pressure is not what would cause the ball to "bump up". Its the initial acceleration. No pressure, no acceleration so pressure is part of it. BP produces a greater initial acceleration than most smokeless powders and BP will work well with bullets under bore diameter where as most smokeless powders will gas cut bullets that are only a few thousandths under groove diameter. This ability to size the bullets to the barrel is why the various modern ML bullets and the Minie work.
But the balls are so short that its hard for the front of the ball not to move when the back of the ball does. HOWEVER, some of the shadow photos in Lymans BP book show balls that are somewhat flattened.
The acceleration on a longer bullet in a 45-70 etc results in the bullet expanding before it ever moves in the cartridge case. This is easy to determine when PP bullets are fired in a chamber that is more than about .015 longer than the cartridge case. On the smooth sided PP bullet the mark where the patch is cut off by the gap is easy to see. The paper ring often is bonded to the case mouth sometimes. With naked bullets the mark on the recovered bullet is harder to see due to lube grooves that are often at the case mouth with the bullet seated to the desired depth.
Heavy bullets will easily bump up .015 or more.

Round balls have far less inertia and thus do not bump up as dramatically. I am sure there is some expansion but I doubt its more than .001 or so. Its certainly not enough to cause patch weave to show where the grooves are.

Dan

 

[longcruise]

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.

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

I blew your pic up in a photo editor and do see something there but it pixilates pretty fast. In any case, I never doubted they were there, but simply was advising you that they did not show very well. Would show much better if you set your camera for a very large size pic with as fine a resolution as possible and then crop down to the ball for a large image of the ball with better resolution. Cropping will reduce the pic size at the same time to fit the thread without making it a mile wide.

You and Dan both bring the conicals into the discussion, and that's just fine. I understand the physics of the conical bumping up. What differs, IMO, is that the conical is a column of lead that is squashed down by the inertia of the entire column with the maximum force applied at the base of the bullet and the force lessening toward the top of the column (nose of the bullet). Then, you have the ball which would seem at first glance to be effected the same as a column of lead. But, the distribution of the lead in the projectile is also important. The maximum inertia effect on a ball is at the dead center of the "top" if you want to imagine a column of lead only through the center of the ball. But, the pressure beneath the ball is still acting to keep the entire ball round. It counteracts the bumping up of the ball from all directions on the bottom half of the ball.

Weight should not be a factor as much as the length of the lead column. For example, a 60 grain .224 caliber lead bullet will bump up right along with the 45-70.

Comparing a column of lead to a round ball of lead is apples to oranges.

 

[paulab]

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

 

[CoyoteJoe]

Dan & marmotslayer, I think we are on the same page, oburation occurs when the force of acceleration working against the resistance of inertia exceeds the yield strength of the lead allow. It would be a balance of the two opposing forces, decreasing one would require increasing the other to achieve the same effect. As a wild example, if we start with a .50 caliber bullet 6" long it would not take much powder to fully obturate the base due the the great resistance of inertia. Cut the bullet to 3" long and it would require more powder, producing greater acceleration, to achieve the same degree of obturation since the inertial is less but still considerable. Cut it to one inch long and considerably more powder, producing a much greater force of acceleration would be required to obturate since the inertial resistance would be considerably less.
There is no doubting that a lead ball will obturate if given sufficient acceleration. The question is whether normal rifle loads do achieve that rate of acceleration.
Marmotslayer, I don't think it is apples to oranges at all. I believe we can think of a ball as just a very short bullet, the shape of the nose and the base being immaterial.