Any formulae for predicting efficacy?

[481]

My only reservation is that WCs, looking at those I can get, have 60% of the muzzle energy and 70% of the velocity, when compared to the two jacketed variants. Not to mention having 9gr lighter bullets.

OK, for the sake of looking at what such a round would do, I am assuming that we are still talking about .38-caliber for the bore, and being 9 gr. lighter that must be a 148 gr WC, and 70% of 800 fps means that your WC is buzzing along at what? 560 fps?

So just running those specs through the two formulae...

The Schwartz bullet penetration formula says that such an animal would give you about 13.9 inches of penetration and permanently crush 23.6 grams of ballistic gelatin while the MacPherson bullet penetration formula says that the very same arrangement would give you about 16.3 inches of penetration and permanently crush 29.2 grams of ballistic gelatin.

The MacPherson prediction seems to my eye to be a little 'optimistic', but otherwise both formulae seem to generally agree that you'll see about 15 inches of penetration and about an ounce of crushed gelatin/tissue.

 

[481]

481 - I'll take your word for it.
As I get older and older, I've become more of a visual type.

I like the ease of seeing something in a video - such as the bullet going through the gel - and the way it's path & the shape of the bullet is right there to see.

Hey. Every day that we can achieve a voluntary vertical orientation is a good day. The "visual stuff"- yeah, I like that, too.

Nothing beats watching a gelatin test at high frame rate.

 

[Pond James Pond]

OK, for the sake of looking at what such a round would do, I am assuming that we are still talking about .38-caliber for the bore, and being 9 gr. lighter that must be a 148 gr WC, and 70% of 800 fps means that your WC is buzzing along at what? 560 fps?

Uhh.......I'd just like to say maths is not my strong suite, especially when I guesstimate.

The actual figures for the jacketed cartridges and WC versions are as follows in m/s: 271 and 213 respectively. These translate to 890fps and 700fps respectively. These are from a 6" barrel on the manufacturer website. So I guesstimated again as to what that might mean from my 2" and I came to about 800fps and 670fps. Having now taken the 17 seconds needed to open and use the calculator I can now confirm that the WC has approximately 84% of the jacketed rounds... (what's 14% and a 2x over-estimation amongst friends, eh?)

 

[481]

Hell, most days I have all I can manage with just trying to keep the darned checkbook balanced.

Revised predictions (assumes no expansion) for the .38 Spec. 148 gr. WC using the corrected velocity of 213ms^-1 (or 700 fps):

Schwartz formula: Pen. = 16.6 inches, Wound Mass = 28.2 grams

MacPherson formula: Pen. = 20.2 inches, Wound Mass = 34.4 grams

 

[Don P]

My one and only question is if there is a way of approximating, on paper, how a given round might perform in an SD situation given the parameters I have avaialble.

For me simple, accuracy is job 1. Doesn't matter what round you choose is you cannot hit that proverbial side of the barn.
Just my .02 worth and that is for free.

 

[Pond James Pond]

For me simple, accuracy is job 1.

I agree, but CCW with my .308 proved quite tricky, so I dropped the 0.

 

[Derbel McDillet]

For me simple, accuracy is job 1. Doesn't matter what round you choose is you cannot hit that proverbial side of the barn.

Placement + penetration are the keys to damaging vitals and quickly stopping a bad guy.

If you have good placement but the bullet doesn't penetrate deeply enough to reach vitals then all you've accomplished is to create a non-vital wound and the bad guy is not compelled to stop.

Likewise if the bullet penetrates deeply but doesn't pass through vital tissues because of poor shot placement then the same situation exists - a non-vital wound.

 

[481]

Placement + penetration are the keys to damaging vitals and quickly stopping a bad guy.

If you have good placement but the bullet doesn't penetrate deeply enough to reach vitals then all you've accomplished is to create a non-vital wound and the bad guy is not compelled to stop.

Likewise if the bullet penetrates deeply but doesn't pass through vital tissues because of poor shot placement then the same situation exists - a non-vital wound.

This.

 

[WESHOOT2]

Unfortunately, human target media is not repeatable.