What’s wrong with the description “high caliber weaponry”?
Have you ever been shot at by .50 cal rounds? I have.
Each round is about 10 or 12 inches long, a giant bullet....
A hauntingly slow and steady discharge in one to two second intervals and the shooter usually walks them into the target.
Whatever you're describing, it isn't a .50 cal.
“high caliber” is a nonsense term. It is either a large caliber or a high powered weapon.
A high caliber sounds like something fired from a mountain top or by a valley girl in middle school.