From personal experience shooting junkers:
1-oz 12-ga slug (I like Winchester and Remington) fired from a 18.5" double barrel coach gun will breeze right through the grille, header panel, condenser, radiator and it hardly notices it.
On a 85 Chevy truck, it did embed itself into the timing cover of a small block Chevrolet V8. It will break the water pump housing if you hit it. Afterwards the motor still ran as well as it did before (Since it was getting junked, not well, but that had nothing to do with the slugs.)
Tests with a 3800-V6 Pontiac Bonneville showed the slug goes right through all of the above, through the plastic valve cover and into the intake manifold.
At another angle it did destroy the coil pack assembly just above the alternator (which would stop the engine). In this case the motor was seized before I started shooting it so I don't know if the slug in the intake would have done anything but make a massive vacuum leak.
Similar testing with a 1988 Toyota 4x4 V6 truck had the slug blow right into the timing cover and water pump without any trouble and wreck the timing belt. This did shut the motor down immediately. The second slug shot the distributor right off the cylinder head.
IN all three cases I was deliberately trying to inflict damage to the vehicle to simulate a "roadblocking" sort of situation. Firing was done at about 10 yards maximum. All vehicles were rusted out junk I was taking in for scrap anyway.
Bear in mind that even with the motor disabled the car would still be rolling.
I also did some tests involving windshield penetration- in all three vehicles the slugs were fired from about six feet in front of the car, penetrated the windshield, deflected slightly, and continued through the drivers' seat.
The Chevy pickup, the slug went through the back wall of the cab, through the front of the bed, through the bed floor, and into the ground.
The Pontiac Bonneville, the slug went through the front and rear seats and embedded in the spare tire in the trunk.
The Toyota truck, the slug went through everything and hit a frame rail and splattered.
All three vehicles, the slug went through the driver door, through the passenger door, and out into the woods. Exit hole was big enough to put three fingers into.
I did some similar testing with regular #8 shot 1-oz loads, and at about 10 yards the shot does not penetrate an automotive sheet metal panel (like a door or hood) but it will dent the heck out of it and scour away the paint. When standing within 3 feet of the panel it does make a fist-sized hole but doesn't do more than make a spatter on the seat inside.
My scrap dealer wants fuel tanks drained before you bring them in, and my personal method involves my 19" barrel H&R Topper 158, a 1-oz deer slug is fired from above through the floor of the car and into and through the fuel tank. The hole is usually a largish puckered rip that quickly empties the fuel tank. 2-3 of these holes ensure that there is no fuel residue left to the satisfaction of the scrap dealer. IN some case the fuel tank straps are severed by the slug and this makes it easy to remove the tank. Filing the tank with water before shooting it also makes a bigger deformation and can blow the entire bottom out of the tank.
