As Pistolpete mentions plated bullets can be a real problem. I was talking with an old gunsmith buddy last year and he told me about stuck plated bullets. They aren’t truly jacketed just thin copper plating and they upset or obturate to a degree in the barrel. He told me they were sometimes impossible to drive out. So when he runs into one like that he plugs the barrel and pours some copper cleaner like Sweets with lots of ammonia in the bore. After a long soak the ammonia eats up the jacket and out comes the slug. Thought I’d mention it

Rick