Penetration of a Sphere formula?

[the Schwartz]

Wonderful, thank you!

While I have you here, how would the performance be for a 0.33" Zinc Alloy 00 that weighs 33.9gr at the same impact velocity?

The ball bearings are a simple and cheap option, but I think the ideal (if penetration is up to snuff) would be a Zinc Diecast 00 buckshot, as that would theoretically be less of a ricochet hazard.

All three penetration models can be used to predict the maximum terminal penetration of a 0.33'' zinc alloy pellet weighing 33.9 grains with an impact velocity of 1,212 fps—

mTHOR: 11.23 inches
Q-model: 12.98 inches
MacPherson: 13.57 inches

If you wanted to get really ''exotic''—and exorbitantly expensive!—you could use pure iridium with a density of 22.55 g/cm³ for a pellet mass of 107.3 grains.

Obtaining 12'' of terminal penetration depth with iridium OO pellets would require an impact velocity of just 350 fps—

mTHOR: 14.08 inches
Q-model: 15.58 inches
MacPherson: 12.11 inches

Of course, a single shotgun shell loaded with 12 pellets of 0.33'' iridium OO Buck would cost about $4,900, so a box of 5 shells would cost $24,500 which seems to be just about in line with current ammunition pricing these days.

[Shawn Dodson]

I have a handful of MacPherson's Bullet Penetration book (second printing) that I discovered in an old moving box. A couple are signed (scribbled) by MacPherson. Some are like-new and some are "good" condition. PM me if interested.

[Archer1440]

I can’t imagine that actual steel bearing balls would do much good to the inside of a shotgun barrel... They’re considerably harder than typical barrel steels.

[Jim Watson]

Right. There were some barrels ruined by Daisy BBs in the early steel shot era. Steel shotgun pellets are very mild steel, fully annealed and in thick tough shot cup wads. I don't know what kind of wad it would take to protect a shotgun barrel from steel buckshot, especially hardened bearing balls.

Zinc is a better choice.

But what did you say the advantage would be? Cheaper? Shoot a lot of intruders, do you?
Low recoil? I don't know what the penetration of the typical "tactical" buckshot at Skeet velocity is, but probably adequate.

[spyderco monkey]

Right. There were some barrels ruined by Daisy BBs in the early steel shot era. Steel shotgun pellets are very mild steel, fully annealed and in thick tough shot cup wads. I don't know what kind of wad it would take to protect a shotgun barrel from steel buckshot, especially hardened bearing balls.

Zinc is a better choice.

But what did you say the advantage would be? Cheaper? Shoot a lot of intruders, do you?
Low recoil? I don't know what the penetration of the typical "tactical" buckshot at Skeet velocity is, but probably adequate.

I was originally looking into Zinc/ZAMAK when I stumbled across the bearings. Thats still ideally what I'd like to see happen, especially since Zinc can be easily die cast and even gravity cast.

The goal was to get a really low recoil 12 gauge ammo.

9x 33.9gr ZAMAC buckshot would be 305gr/0.687oz.

@ 1400fps, that would have a power factor of 427

That would offer comparably low recoil to a .410 5x000 load, which @ 1135fps has a Power Factor of 397, and quite a bit lower then PF 554 for lead based 'reduced recoil' 12 gauge 00.

[Jim Watson]

The largest steel shotgun shot I can find is F size at .22" diameter. (No 4 buck is 24")
There are specific hard metal wads and Mylar wraps to protect the barrel.

I guess you could get in multiple wraps to cover bearing balls but best to have a cheap barrel for testing.

[Baldanders]

All three penetration models can be used to predict the maximum terminal penetration of a 0.33'' zinc alloy pellet weighing 33.9 grains with an impact velocity of 1,212 fps—

mTHOR: 11.23 inches
Q-model: 12.98 inches
MacPherson: 13.57 inches

If you wanted to get really ''exotic''—and exorbitantly expensive!—you could use pure iridium with a density of 22.55 g/cm³ for a pellet mass of 107.3 grains.

Obtaining 12'' of terminal penetration depth with iridium OO pellets would require an impact velocity of just 350 fps—

mTHOR: 14.08 inches
Q-model: 15.58 inches
MacPherson: 12.11 inches

Of course, a single shotgun shell loaded with 12 pellets of 0.33'' iridium OO Buck would cost about $4,900, so a box of 5 shells would cost $24,500 which seems to be just about in line with current ammunition pricing these days.

Why not osmium? 😉

Although, if asteroid mining ever made that feasable, gold would probably be cheap enough too.

[Jim Watson]

Trivia:
The Army once studied, maybe prototyped a handgun firing tungsten No 4 out of a .45 shotshell. I forget how many in the load.

[Baldanders]

Trivia:
The Army once studied, maybe prototyped a handgun firing tungsten No 4 out of a .45 shotshell. I forget how many in the load.

What was the intended purpose?

[Jim Watson]

Well, the very short American Rifleman blurb did not go into doctrine, but I suppose it was meant for less practiced troops to defend themselves from foreigners with.