Half baked idea: The odd ball

[Canute Rex]

I was thinking about round ball aerodynamics, the "roughen your round balls like golf balls" debate, and all that. One of the things that slows a round ball in transit is wake turbulence - the energy spent by the air rippling into the low pressure area behind the ball.

Imagine a teardrop shaped "round" ball. It would be hemispherical on the sprue end and taper back to a rounded point on the aft end, like an exaggerated boat tail bullet for a modern rifle.

It would take a larger patch than usual for its diameter, and it would require some careful sprue centering to avoid tail wiggle. I wonder how much it would improve the aerodynamics, if at all, and how much of an extended tail it would need to make a difference.

I have to admit that this is a completely frivolous question. I suppose I could make a cherry and try it out.

Two-bit opinions? Six-bit opinions?

[Jerry V Lape]

Question has long ago been answered - that is why we went to bullets vs balls mid 1800s and later to longer bullets with improved shapes.  The boat tail being a tweek on the bullet shape.  Why would you want to struggle with loading an intermediate shape, admittedly difficult to load and clearly less aerodynamic than a bullet.  As to whether your proposal would enhance roundball performance - it wouldn't be a round ball any longer and as you tweeked the shape to make it workable you would wind up with a bullet - having reinvented the wheel.     

[smylee grouch]

I wonder if the so called added performance would be worth the effort when the round ball does a good enough job on its own. Increase your powder charge and bore size. JMHO      Gary

[David Fox]

And, extremely long range bullets intended for match and and sniper use are also usually boattailed to boot and sometimes have extended 'noses' which, one understands, not only minimize drag but also better deal with atmospheric variations encountered in flight.

[Dphariss]

I was thinking about round ball aerodynamics, the "roughen your round balls like golf balls" debate, and all that. One of the things that slows a round ball in transit is wake turbulence - the energy spent by the air rippling into the low pressure area behind the ball.

Imagine a teardrop shaped "round" ball. It would be hemispherical on the sprue end and taper back to a rounded point on the aft end, like an exaggerated boat tail bullet for a modern rifle.

It would take a larger patch than usual for its diameter, and it would require some careful sprue centering to avoid tail wiggle. I wonder how much it would improve the aerodynamics, if at all, and how much of an extended tail it would need to make a difference.

I have to admit that this is a completely frivolous question. I suppose I could make a cherry and try it out.

Two-bit opinions? Six-bit opinions?

The historical alternative to the RB in America anyway, is the picket bullet. But...
They require a faster twist 30-36" and tools to load them straight. And they were generally flat based. Round bases apparently don't shoot well. The ones I made didn't.
The round ball was the typical hunting bullet until the advent of the breechloader.
Because bullets do not stay on the powder unless cloth patched and pickets are a PITA to load if any accuracy is to be obtained.
Yes I am sure some hunters used bullets the British were pushing "expansive" bullets probably by the 1840s or so. Much to dismay of some hunters. But then as now some folks were enamored with new and improved even if it were just new and no improvement and often a step back.
There is a 3 cavity bullet mould marked A Gumph on page 116 of Whiskers "Gunsmiths of Lancaster County" Round, Picket and a round ended double ball thing. So you are not inventing something new.

Most match bullets shot with BP  from slug and cartridge guns were flat or have a small cavity in the base and historically were usually paper patches and at least 3 calibers long.The slug does not necessarily need a starter if bore sized. But slug guns invariably have false muzzles.
Dan

[hanshi]

A dimpled (like a golf ball) rb does have an advantage over a smooth rb.  This advantage, though real, is still very tiny.  It's a lot of trouble to go to in order to get performance that a few extra grains of powder will provide.  Everything considered, the historically proven prb is as good as it gets without going to a genuine bullet.

[Dan]

Aerodynamic drag on bullets is broken down into three components: Nose, shank and base. Shank drag usually runs in the 5% range and base drag around 7% for flat base bullets. These numbers are likely different for a round ball, but not so different as to matter a lot.  Nose drag accounts for the rest and is a function of form and cross sectional area.  The idea of a tear drop form does present potential for drag reduction, but it is a theory fraught with headaches that even in a perfect world provides little return.

And...what Mr. Phariss said...in spades.  I've played with the picket bullet and they are a puzzle.

[Canute Rex]

Well then...I'd better go cast some truly round balls.

Even 10% reduction in drag wouldn't be worth the hassle. Thanks to everyone for weighing in. I always learn something around here.

[northmn]

Your concept might work, and in theory is sound.  A teardrop loaded properly would have the shuttle cock, nose heavy effect similat to the Forster shotgun slug.  However, questions arise as to whether it would tend to stabilize itself or start to tumble.  If it were to tumble you would have the same effect as a keyholing bullet and probably would really start to go off in unusual direstions.  It was said that the old drop shot,  tear dropped shaped, patterned better than some of us would think because the weight forward nose sections tended to stabilize the shot in flight so that it would head more or less straight.  It also was said to have better penetration.  Still if you look modern trap loads are loaded with very round shot hardened to avoid deformation so that the most shot goes into a pattern.  I persoanlly think that a slight teardrop would work, but it would require very careful loading.  It might be like the choke in a shotgun where Forseyth had over choked and had worse patterns than an open choke until he thought he had removed the choke and found out how small of constriction was needed.  I think that a slight teardrop or oblong to one side might work well, but that a true pointed teardrop may be overdone.

DP   

[BrentD]

You will have a severe problem getting the tail of your teardrop exactly straight behind the bullet.  And then you will also have an issue of keeping the teardrop shape when the bullet obdurates to fill the grooves.  The latter can be overcome, the former not so much. 

[Dphariss]

You will have a severe problem getting the tail of your teardrop exactly straight behind the bullet.  And then you will also have an issue of keeping the teardrop shape when the bullet obdurates to fill the grooves.  The latter can be overcome, the former not so much. 

You are correct.
I don't think is possible to load straight. Its impossible to center the tail and it will unbalance the bullet.

 Even with a fairly long rod end fitted to the bullet shape and the bore it still would not shoot a round base pointed picket loaded point to the front where it could be controlled to some extent.
A guide starter was needed and I eventually made one went to a flat base/flat point design its hows promise so far has shot best with 80 grains of FF swiss in a 40 caliber.


Dan

[BrentD]

Yes, I have messed with boattailed bullets or my own design in BPCRs and it can be done, but the PITA issues to overcome coupled with the requirements for super fast twist barrels - it just ain't worth it.  But everyone has to try at least once.  Boattailed "roundballs" would be the worst.

[Dphariss]

And, extremely long range bullets intended for match and and sniper use are also usually boattailed to boot and sometimes have extended 'noses' which, one understands, not only minimize drag but also better deal with atmospheric variations encountered in flight.

The problem with BP is bullet upset. BP will deform bullets made of soft alloys. This is why slug guns historically shot bullets cast in two pieces and swaged together, soft base - hard nose.
A long skinny nose like found on a Berger bullet in .264 or .308  will slump when fired with BP unless very hard. Something like Lymans #2 alloy. I had a 380 gr bullets from Hoch mould that was very accurate in #2 but if cast 1:40  it would full keyhole  at least one shot in 5 at 100 yards.
People are shooting long bullets in 38 caliber BPCRs with significantly faster twists that are needed for a 3-3.5 caliber bullet. The problem with cast lead bullets and fast twists is that cast bullets are never perfect and the fast twist can be a cause of fliers.
I have a rule of thumb... If I want to shoot bullets I use a BPCR. If I want the shoot low drag bullets I shoot something like my AR or 6.5 Swede.
The near ultimate right now in low recoil, low drag and flat trajectory is the 260 Remington.
But this is pretty far from shooting a traditional American Long Rifle.
When a person decides to shoot and hunt with a traditional ML the shooter needs to accept the fact that its impossible to shoot .600 BC bullets and understand that while certainly not the ideal projectile from the exterior ballistic standpoint the round ball works very well for hunting and target shooting WITHIN IT'S RANGE. So folks are better advised to find  the best  load for their round ball rifle and practice with it and quit agonizing over trying to get the rbs hunting range extended by 25 yard or increasing its "remaining energy".
If the best ballistics are a concern then folks should buy a 260 Remington and a set of loading dies.

Dan

[smylee grouch]

Amen Dan; ya took the thoughts right out of my mind>   Gary

[northmn]

The discussion of roughened round ball was concerning smoothbores.  In a rifle a teardrop shape could cause some interesting results as the spin in a off center point could cause an interesting woddle.  In a smooth bore with the tail loaded down you may get a weight forward type action where the tail actually goes to balance. Mostly I agree with Dan's philosophy in that it would be a pedantic exercise and that a round ball would be as effective in practical use.  If a 20 bore seems to have insufficeient weight for whatever uses one may have for it, then a 12 or 16 ga is in order.  Look at the ridiculous ammunition they push off for "modern" muzzleloaders.

DP