Through 3/4 inch plywood and into ballistic gelatin
“Going by various nicknames such as : “street sweeper” and “riot gun”, the 12 gauge shotgun, using buckshot, has a well-earned reputation for effectiveness during close-range shooting events.
Good pump action shotguns from Mossberg, Remington and others may be purchased for no more than $300 – about a third of the asking price of the AR-15 and similar rifles and having a terminal effectiveness far out of proportion to the price of the gun itself.
Using a standard 10 pellet, 000 buckshot load, one shot from a 12 gauge is equal to a 10-shot burst from a 9x19mm submachinegun – with all FMJ bullets impacting at almost the same instant.”