Fire swaging a cylindrical into a hexagonal

[Widows Son]

Hello all. I have another question regarding loading a Whitworth. It is well demonstrated that a cylindrical bullet be obturated into a hexagon by the energy of the exploding powder. But….does this require a cupped or hollow base or does it still work with a flat bottomed projectile?

Regards

 

[TFoley]

I guess, that after having posted this image about fifty times that this will serve to answer your question.

 

[Widows Son]

A pic is worth 1000 words!
That must be a flat bottom bullet

 

[nkbj]

Hello all. I have another question regarding loading a Whitworth. It is well demonstrated that a cylindrical bullet be obturated into a hexagon by the energy of the exploding powder. But….does this require a cupped or hollow base or does it still work with a flat bottomed projectile?

Regards

Whitworth bullets, being long and heavy, have enough inertia to initially resist forward movement. The rear of the bullet compresses while it is trying to push the front part on down the barrel. The lead squishes sideways like smashing an uncooked biscuit on the kitchen counter. Over time, traversing a few inches of barrel, the squishing effect travels up the length of the bullet.

I've been studying on that process for years, not with a Whitworth but with a number of different rifle and revolver calibers. Once your bullet gets short enough (not the problem with a Whitworth!) and the powder charges small enough, it becomes a problem to reliably, consistently produce the effect and to seal the bore. That's when hollow bases really come into their own.
Like with these are .36 caliber revolver bullets.

 

[TFoley]

A pic is worth 1000 words!That must be a flat bottom bullet

It is, else I would not have posted it, you having asked specifically about such a bullet.

Holes made by the bullet above show distinct signs of have been hexagonalated.