“Pretty sure a bullet would not stop the engine in my dually—a 454 gas version, which weighs about 550# on it’s own. All cast iron—NO aluminum!”
Actually, it probably would. Magnums have been used for this purpose by police since they were first available. They could break flathead Fords, and “modern” (post-1950’s) engines have better thin wall casting techniques. Some of those old engines were amazingly heavy (with cast-in oil pans) given their displacement.
You might think that an aluminum engine would be better, but the aluminum engine blocks are generally made with high silicon content, and are strong, but brittle.
You're correct. Unless people have actually worked on rebuilding an engine, they may not realize it isn't a solid block of metal. The block has thin walls enclosing water and oil passageways (tunnels). Doesn't take much to penetrate many areas and cause a shutdown of an engine. Often, just simple debris in the air intake (enclosed in plastic) will destroy valves and pistons.