The line between buckshot and birdshot falls between F shot, the largest bird shot, which is .22 caliber, and No. 4 buckshot, which measures .24 inches.

A. Major shotshell manufacturers do not load 00 buckshot in 20 gauge for the simple reason that so few of the large pellets can be loaded into a 20-ga. hull. They do, however, offer 20-ga., 2 3/4 ...