I hear ya. For movies, it's all low-end rumble that gets the attention. In real life there's a loud, sudden impact (KA-RAK!), which is well above the subwoofer range but it's the low rumbly decay that the movies concentrate on. It's more exciting and easier to reproduce.
If you want to hear realistic cannons, Telarc's 5.1 SACD version of Tchaikovsky's 1812 will be a eye opener. One would think that it's your subs that would get the workout, Guess what? You're wrong. IF you play it loud, your midrange driver better be able to handle some serious dynamics.