Some Very Informative test Data with Smaller Buckshot Loads
I found a website that has done some testing of smaller sized buckshot ammo in ballistic gelatine, and the results pretty much have confirmed what I have felt all along: #4 Buckshot offers very good penetration. Even Hevishot's Dead Coyote load using .20 caliber T shot made out of a hard and heavy Tungsten Alloy gave decent penetration.
You can view the data here for yourself on this web page:
The Federal #4 Buckshot load that he tested is the ammo that I have in my shotgun. And it penetrated from 12.5 to 13.3 inches deep at a range of 10 ft. That is more than adequate penetration.
Even the Hevishot Dead Coyote ammo gave very deadly results at 10 ft, with the buckshot penetrating from 8 to 9.8 inches. And if you look at the photos, the size of the wound channels are simply massive. Far larger than what the most powerful magnum handguns can produce.
So I am perfectly comfortable with #4 Buckshot, and see no need at all to increase to #1 Buck, much less 00 Buckshot. The more massive wound channels caused by the far denser patterns produced by these smaller buckshot are going to absolutely devastate any target.
If you check further on the website, you will also see that he has recently done some additional testing with 20 gauge #4 Buckshot ammo, and was able to virtually get the same level of penetration with it too. So I would feel perfectly safe with a 20 gauge spewing 18 .24 caliber #4 Buckshot at a time too.
Here is a link to the 20 gauge testing:
And here is a photo of what one of the Hevishot Dead Coyote shells did to a ballistic gelatin block. Remember that each of the round balls in this photo is .20 caliber. For the first six inches of the penetration, there is easily a cylinder that is a full 3 inches wide for that entire length. That initial area alone works out to 42.5 cubic inches of totally destroyed tissue! For perspective, that is equal to 1.5 liquid pints!!