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.