Lioness show / sig spear

Hey not gonna ruin the show too much but i had a question about the sig spear in season 2.. Am I missing something or are the full auto Spears really that fast? Thing sounds like a mini gun going off when they go full auto? Am I listening to multiple rifles firing simultaneously or are they actually that fast ? I'm probably going to get fried for this but with all the new shit coming out, I just never know anymore. Thanks.