Shiloh Rifle Forums

The modified Elliptical shortens the nose moving the Center of Gravity forward resulting in a lesser yaw angle which means less impact to head winds.

This is modifying the Dynamic Stability.

SchuetzenDave wrote: ↑Fri Jan 17, 2020 8:52 am The modified Elliptical shortens the nose moving the Center of Gravity forward resulting in a lesser yaw angle which means less impact to head winds.

This is modifying the Dynamic Stability.

The thing about a Prolate (lets call it a Prolate because that is what it is) is that we don't have to say "modified". We can say precisely HOW it is "modified" by specifying the axes or the ratio of the three axes (diameters) as the case may be. Personally, in a .45 I like a 1.46" by .443" by .443" .

Nicely, this can be translated to ratios 3.3:1:1, and these can then easily be transferred to other calibers and applied just as easily.

There is value in learning to discuss prolates with some precision. We could all be on the same page then.

BFD wrote: ↑Fri Jan 17, 2020 8:47 am

SchuetzenDave wrote: ↑Fri Jan 17, 2020 8:43 am
However does a poorer BC result in poorer accuracy or just result in more drop over distance?

This is more important for hunting (flatter trajectory) or having your bullet reach further distances; but does it really affect accuracy?

For BPCR Silhouette we are shooting fixed distances so we have already determined the drop of our bullet so does BC really matter?

BC affects wind drift. Higher BCs have less drift and thus if you miss a wind call by say 10%, that 10% will be larger with a low BC than a high BC bullet.

what brent said.
bruce.

elipse/prolate.
former is 2 dimensions, and latter is the same but 3 dimensions.
elipse at least comes form a formula which includes an x axis and a y axis
x axis is based on the length of nose, and y axis is based on bullet diameter.
I prefer to think of these things in calibres, and like the nose to be about 1.5 calibres long.
bruce.

bruce m wrote: ↑Fri Jan 17, 2020 2:55 pm elipse/prolate.
former is 2 dimensions, and latter is the same but 3 dimensions.
elipse at least comes form a formula which includes an x axis and a y axis
x axis is based on the length of nose, and y axis is based on bullet diameter.
I prefer to think of these things in calibres, and like the nose to be about 1.5 calibres long.
bruce.

Do you call a basketball a "circle"?

A prolate comes with a formula with x, y, and z axes. THAT IS THE ENTIRE POINT! There are more efficient nose shapes, and they come with equations too. There is a reason for that, and a lot of reasons to use those equations.

brent,
you are dead right.
I suppose that I am thinking in terms of cross section, where you are more correctly defining the 3d version.
other than that we are on the same page.
bruce.

Yes, we should say "Elliptical Profile", Mod Elliptical Profile, or, in 3D, correctly Prolate or Mod Prolate
Arnie

Corbin gives pretty explanations on ogive shapes. I used to swage a lot of bullets using both of the Corbin's equipment and still do occasionally and I prefer what Corbin calls the 1E ogive. I find this shape for the .45 and .50 to stay accurate as far as my sights will reach. http://www.corbins.com/bullets.htm#elliptical Drop down to the round nosed ogive.

Corbin gives pretty explanations on ogive shapes. I used to swage a lot of bullets using both of the Corbin's equipment and still do occasionally and I prefer what Corbin calls the 1E ogive. I find this shape for the .45 and .50 to stay accurate as far as my sights will reach. http://www.corbins.com/bullets.htm#elliptical

These are some of the bullets I swaged when moulds and bullets I wanted to use just were not available.

Very interesting conversation, have we decided on what twist to use for Sillywet yet?

16, 14.5,14, all three will work just fine