Round ball BCs are low - .045 for a .319" round ball and .049 for a .350 round ball according to Lyman - but people seem to over estimate the velocity loss at social shooting distances - as evidenced by the video posted above and his failure to add extra blocks on the end.

For example,

Published 12 ga #00 buck velocity seems to vary from about 1200 fps to 1600 fps, but let's call 1,350 fps average.

If we consider a pure lead .330" #00 buck ball that weighs 54 grains at 1350 fps at the muzzle and use a BC of .047, we get these velocities:

5 yards = 1295
15 yards = 1200
25 yards = 1122
35 yards = 1061
45 yards = 1012
55 yards = 971

It's essentially a velocity loss of 10 fps per yard, but only until the pellet is sub sonic. Once it is subsonic, the velocity loss decreases to only about 5 fps per yard.

As a result on a 70 degrees F day where the speed of sound is 1128 fps, the difference between 20 yards (1159 fps) and 40 yards (1035 fps) is just 124 fps.

The energy of a 54 gr round ball is not overly impressive at 218 ft pounds at the muzzle at 1350 fps, and

201 ft lbs at 5 yards
173 ft lbs at 15 yards
151 ft lbs at 25 yards
135 ft lbs at 35 yards
123 ft lbs at 45 yards

That compares to a high velocity 40 gr .22 LR with 141 ft pounds at the muzzle and 122 ft lbs at 30 yards.

But...the #00 buck is drilling .33 caliber holes, is still going to give you ample penetration in the 16"-18" range even at 40 yards, and is potentially delivering all 9 pellets to the target at the same time with a pretty useful dispersion pattern that increases the potential for an effective CNS or cardio pulmonary hit.

That combination of penetration, .33 caliber holes and useful dispersion with a high probability of a vital hit is what makes a 12 ga 2 3/4" #00 buck load with 9 pellets very effective at stopping assailants. A 12 ga 3" #00 buck load with 12 pellets is even better.

Pure lead or copper plated shot?

If you go with pure lead shot you'll possibly get some expansion of the pellets. But there is no free lunch as you'll also get more shot deformation in the barrel than with harder copper plated shot and you'll get larger patterns.


#00 buck (54 gr, .330") versus #4 buck (21 gr, .240") versus #4 birdshot (3.3 gr, .130")?

All of the above have their fans but #00 buck is the only one that delivers adequate penetration and it is I think the sweet spot in size, weight and number of pellets.

Penetration with #4 buck drops to 8 to 12" and with #4 birdshot penetration falls to 4 to 8". That just isn't enough.

Plus as the pellet size gets smaller so does the BC, and consequently velocity loss rapidly increases.

The downside is that heavy clothing presents a pretty significant impediment to penetration with all of the above small round balls as even #00 buck is pretty light and lacking in sectional density.