I ran a series of tests out of three 12 gauge shotguns, a Marlin 500, a Winchester 1400, and an Antonio Zoli O/U, using all available sizes of buckshot, in both 2 3/4 and 3 inch shells. My criterion was to try to get 140 grains of lead in a nine inch paper plate. The plate approximates the size of the vital area of a grown deer. 140 grains is a figure that is considered the minimum to drop a deer. It is two 000 buck pellets, three 00 buck, or seven 4 buck. I tried chokes from cylinder to full, and was not able to meet the standard consistently at 30 yards with any combination. I really hoped that the 000 loads would produce, as only 2 pellets were needed to meet the standard, but none of the guns and choke combinations I used met the test.
I also tried 16 and 20 gauge loads in one gun each, and they were no better. I did kill a deer with the 16 gauge the next year. I shot twice and the deer had two pellets through the lungs when recovered. The range was twenty-five yards.
I have hunted with the 12 gauges guns since, and load 000 buck. If I were to take a shot, it would have to be no more than twenty-five yards, and I would like to be closer than that.