Biggest Buckshot normally loaded in 20 gauge is #2 Buckshot. Federal has a 3 inch 20 gauge mag load that will hold 18 #2 sized Buckshot.
A 20 gauge shotgun, whether it is loaded with #2, #3, or #4 Buckshot is going to be a very formidable self-defense weapon. In fact, it is probably the better gun for most homeowners to use, due to its lower recoil.
12 gauge Buckshot loads really recoil very badly. A gas operated semiauto shotgun will reduce the recoil effect some and soften it. If you are shooting a pump gun, though, your shoulder will really get slammed.
Only men with real high testosterone levels shoot 12 gauge Buckshot ammo.
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