very slow twist

[Artificer]

Uh, Dave,

You do realize the size targets used for the Baker were SMALLER than what you fired on at the 200 yard line on active duty? The 5 ring bullseye was 12" in diameter, the 4 ring was 24" (same width as the Baker target), the 3 ring was 36 inches and the 2 "ring" was the entire 6 foot by 4 foot target. Just because a target is big really doesn't mean much with good marksmanship and a good rifle.

I just can't get it out of my mind the British Shooter who recently fired his Original Baker rifle at 200, 300 and 400 yards OFFHAND and put the first shot into pretty much the center a man sized silhouette at each distance. He used an original mold, but I don't know if he used leather or cloth patches.

There were recorded kills with the Baker during combat, somewhat beyond 400 yards during the period as well, though most likely shot from some kind of a rest.

OK so?

You are talking about ONE rifle, with ONE shooter, in ONE event. You may in fact be talking about a person who would be a distinguished marksman with that weapon, and proclaiming that the majority of the shooters would do as well.

The British Standard said that at 300 yards if you put all of the ball 3" above the ground into the target, that was the same as hitting the center of the target. If it was common place to do much better, then they would have had different standards.


There were recorded kills with American Long Rifles at 400 yards. (iirc) There is one at that range with a bess. Jacob Deverbaugh fired at 100 yards at a barrel head, 100 times [standing], and did not miss. This was recorded by Daniel Morgan in the 1760's. He picked his best shooter..., not his average shooter.

LD

Dave,

The example of the British Shooter who shot and hit offhand at 200 to 400 yards is not just the test or skill of the Shooter, but also the test of the rifle. If the Rifle wasn’t accurate enough to do it, it would not matter how good the Shooter was. Also, Baker Rifle Shooters did not shoot offhand at those ranges, they shot from the prone or a rest, which imparts much better average accuracy, as you know.

I mention the following to example to demonstrate the importance of the accuracy potential of a rifle and not just the shooter. I was only a week beyond my 18th birthday when I went to boot camp. I had never fired a centerfire rifle in my life before Boot Camp, though I had done a lot of hunting with shotguns and some .22 cal. rifle and pistol hunting and plinking. Less than two months later on Qualification Record Day, I fired 7 straight Bullseyes in a row, Offhand from 200 yards. The 8th shot was also a Bullseye, but I had not lined up correctly on my target and shot “my bullseye” into the target next to mine ”“ so it was a Maggie’s Drawers. I was nowhere close to being a Competition Rifleman, let alone a Distinguished Rifleman. However, that standard military M14 was MORE than capable of that kind of accuracy. Had I been firing on the Baker Rifle Target, instead of the larger target we fired on, it would have been a total of 8 hits out of 10 at 200 yards, Offhand (with ONLY less than a week’s experience firing a large caliber rifle) and that was from a RAW Recruit, who was never good enough to be a competitive shooter.

I am only aware of two examples where American Riflemen shot at or beyond 400 yards in the AWI, though there may be more of which I am unaware. (If there are more, I would love to read of more.) These examples were Timothy Murphy at Saratoga and an unidentified Rifleman who shot at Banastre Tarleton and George Hanger in the Carolina’s.

I have to say I discount the Tim Murphy shot because of many reasons not limited to: 1. There were accounts that 2, 3 and up to 5 riflemen all shooting at the same time (which makes sense), 2. Two British Accounts from the battle mention an old man came out on the flank at a distance of only 60 yards and shot General Simon Fraser; and most importantly 3. Tim Murphy NEVER claimed he had made that shot. To me the most believable account of that story I ever ran across was the range was actually about 285 yards and other riflemen were shooting at General Fraser as well. That makes sense both because it was a believable range and more importantly, the added shooters no doubt acted as “Spotters” on where they were hitting.

The account of the unidentified American Rifleman who shot at Banastre Tarleton and George Hanger at 400 yards in the Carolina’s was a very good shot, BUT even though it was in PERFECT range and weather conditions AND he fired from the prone while taking time to make the shot, the Rifleman MISSED both Officers and their Horses. His shot did take out the horse of the “Bugle Horn Man” who was behind the Officers and sort of in between them, so it was a close miss.

The smaller calibers of the AWI American Rifles did not “buck the wind” and were not as accurate to the range of the larger caliber Baker Rifle. That was part of the reason they went with the larger caliber, because they knew it would be more accurate at longer ranges.

Also as you know, the British Army selected only their best marksmen to be in the Baker Rifle Corps. So even the lower grade marksmen in that unit were better to a lot better than the average British Soldier at marksmanship. Yet even the best marksmen can not make a rifle shoot more accurately than what it is capable of shooting.

Gus

 

[Artificer]

When I say my smoothbore ball has no spin, I mean to say it has no spin induced by rubbing against the side of the bore, so that it has zero spin when it exits the muzzle. That's true whether wadded or patched.

Spence

Spence,

Thank you for the information/clarification.

I'm fairly sure that if MOST people in the 18th century got 4" groups or less from a smoothbore gun, at 100 yards from a rest like you do; they would have been extremely to unimaginably happy with that level of accuracy. However, I strongly suspect they never got close to that level of accuracy with a smoothbore in that period.

You have posted many original quotes on how bad many ball molds seem to have been during the period. That would surely explain some to a lot of the lower level of accuracy. The quality of powder was also "sketchy" at times and that would have hurt accuracy as well.

What we do know is that in the late 17th century, New York's Governor Thomas Dongan reported in a letter to (I think) the Pennsylvania Governor that out of the 5,500 Militia assembled in New York, about 10 percent had rifles. That would make it over 500 rifles in a period LONG before much rifle making went on in Pennsylvania. So even at that early of a date, the rifle was already proving to be the choice of some frontiersmen/Militia Men and would grow in their use in the next century.

Perhaps the reason is that with the limitations of the guns, molds and powder at the time; it was more necessary to have chosen a rifle for accuracy than it is today?

Gus

 

[George]

What I'm really interested in about this problem is not what happened in the old days, but what is the case today. The physics involved. Divorced from all complicating factors of shooters, sights, loading procedures, etc., etc., are there physical reasons that balls shot from smoothbores can never be as accurate as from a rifle? A twist rate of 1:120 or, as I have read of, 1:140, is not much twist. Could even that little bit be eliminated and still shoot accurately?

Another thread is running about accuracy of small caliber smoothbores. It's too bad no one is coming forward with some hard-nosed experience to share in that thread, because I've seen some really excellent shooting with them, and I believe they might be the answer to my question.

Spence

 

[Grenadier1758]

Dave,

We replicate the Deverbaugh match at the April Trade Faire at Fort de Chartres. I think we brought the barrel head into a more reasonable 60 to 80 yards. The barrel head is a steel disc about 8" in diameter.

Winds were really bad this year the winner hit the barrel head three times before he missed.

From modern experience we can see that the ability of a shooter to hit a target is quite varied.

 

[coloradoclyde]

Could even that little bit be eliminated and still shoot accurately?

Sure!.....But then you have to define accuracy..
Will it shoot accurately?....YES! but all other things remaining equal, never as accurately as a rifled gun...

 

[Artificer]

are there physical reasons that balls shot from smoothbores can never be as accurate as from a rifle? A twist rate of 1:120 or, as I have read of, 1:140, is not much twist. Could even that little bit be eliminated and still shoot accurately?

Spence

Short answer at least for now, No, I don't believe it is possible and especially not at the velocities of ML firearms using black powder.

Gus

 

[M. De Land]

A steel ball remains round but not so with a lead patched ball. When it leaves the muzzle it now has a waist and the profile shape is more of an ellipse than a sphere.
An ellipse needs rotation to remain stable in flight past about 50 yards but a perfect sphere dose not.
A case in point in civil war smooth bore cannons shooting iron spheres that retained their round shape and were superbly accurate out to 4-500 yards.
Civil war smooth bore mortars were very accurate to two miles and the 13 inch guns shot a 200 plus pound round shell with a Boreman timed fuse.
The Star Spangled banner written by Francis Scott Key was more about mortar fire than pointed cannon shells, primarily.

 

[George]

A steel ball remains round but not so with a lead patched ball. When it leaves the muzzle it now has a waist and the profile shape is more of an ellipse than a sphere.

Back when I first started thinking about such things, and before I had ever shot a smoothbore, I thought maybe that was the answer to why such slow twist worked. Bullet upset or 'obturation' was considered a real thing by some, and I thought that might change the ball into a ball with a belt. We loaded pretty tight back then, too, and I always suspected that forcing a very tight ball into the bore probably did the same thing, swaged it into a ball with a belt. Either one would make the ball into a very short cylinder such that a very slow twist would stabilize it. Haven't completely given up on that idea.

Spence

 

[coloradoclyde]

The twist rate really isn't that slow once you factor in velocity and calculate your RPM's

Remember most smoothbores weren't supersonic...
But when rifled long guns came along they went supersonic...

The slow rate of twist in early rifles was probably more of a manufacturing limitation than anything else....

 

[George]

Remember most smoothbores weren't supersonic...
But when rifled long guns came along they went supersonic..

I'd like to see the source for that, please. I don't believe it.

Look at this link:

http://arc.id.au/RobinsOnBallistics.html

Scroll down to:

Prop VIII. To determine the Velocity, which any Ball moves with at any Distance from the Piece, it is discharged from.

Notice the velocity reported. That was from a smoothbore musket shooting a .72" ball.

BTW, the speed of sound is 1100+ fps.

Spence

 

[coloradoclyde]

OK! great link...

But, I did say "most" and he was measuring muzzle velocity and I neglected to mention down range velocity..... :haha:
The reason I mentioned supersonic vs. subsonic velocity was because, it makes a difference in stability .

 

[George]

But, I did say "most" and he was measuring muzzle velocity and I neglected to mention down range velocity..... :haha:

How about velocity in the pouch before you load the ball? Or, on the other side of the deer after a passthrough?

The reason I mentioned supersonic vs. subsonic velocity was because, it makes a difference in stability .

Just because A is true and B is true doesn't mean that C is true. It's such a common logical mistake in these discussions...a baseball pitcher throws a knuckle ball and it jinks, roundballs from smoothbores seem to jink, so, ergo, jinking roundballs from smoothbores are caused by the same thing knuckleballs are...golf balls have dimples, they go further and fly straight, we want roundballs to go further and fly straight, so dimples are the answer...sonic transition causes changes in trajectory, our roundballs sometimes change trajectories, has to be transonic turbulence.

It ain't necessarily so.

Spence

 

[coloradoclyde]

True!....There are many variables...identifying which variables are affecting your accuracy can be difficult if not impossible.
However eliminating as many variables as you can, is what accuracy is all about.

 

[M. De Land]

I do know for a fact that more stability disturbance is caused in the transonic flight region than either super or subsonic and it is over a range of deceleration not just one point at the sound barrier.
We find this in our black powder cartridge projectiles and try to push them as fast and as far down range as practical before they inter the transonic region and really get buffeted as the pressure wave moves off the nose and induces yaw.
This of course is far less prevalent in it's effect on a sphere that does not really care much about an over turn moment.
We notice the transonic effect on bullets starting at around 1300 fps down through about 950 fps and then seems to back off from yaw inducement and allow the bullet to settle down again.
An ellipse would most likely be effected much more than a ball by the same pressure wave moving off the front of what amounts to a small bullet ogive,the shape produces.
Having enough projectile rotation is what keeps the over turn moment from winning the struggle and causing a tumble and complete accuracy loss.

 

[coloradoclyde]

This of course is far less prevalent in it's effect on a sphere that does not really care much about an over turn moment.

I disagree....I think this is exactly the point at which a seemingly stable and motionless ball begins to move...Resulting in wobble or the knuckleball affect or whatever you want to call it.....

 

[M. De Land]

My thinking on sphere stability is that it is completely shape induced in the absence of rotation.
This is the reason a smooth bore cannon shooting an iron sphere was and is so accurate to it's effective range.
A patched round ball is not a sphere in flight.

 

[George]

I don't shoot conicals, so have no experience with transonic turbulence such as you describe. From a practical point of view in my shooting, I have shot very good targets at 100 yards with a range of guns, .30, .40., .54 rifles, .55 and .62 smoothbores, all of which went through the transonic range of velocities on the shot, so as far as I can see, it's not bothering my shooting. I think of it as an interesting phenomenon, but purely theoretical as it applies to me and my guns.

Downside of that is that when I miss, I can's say transonic turbulence got me. :haha:

Spence

 

[coloradoclyde]

They all impact the target at subsonic velocities?

I'm curious at what yardage they transition.....

If I were a betting man I would say that the gun that transitions closest to the target is the most accurate and the one that transitions the farthest is the least accurate....Or the gun with the shortest flight time shoots the best.... :hmm:

 

[coloradoclyde]

Do you have any muzzle velocities so I can do some calculations?

 

[coloradoclyde]

Robins proposes that the cause of the lateral or even excessive downward curve of the trajectory is caused by the effect of air resistance on a spinning projectile. He conjectures that when spinning the different parts of the surface of the ball will strike the resisting air at an angle different from the angle at which it would strike if not spinning.

Robins thus described, quite accurately, the effect now usually referred to as the Magnus effect. Newton too, had also described the phenomenon even earlier than Robins.

Isn't Robins making the same stability argument regarding rifling?