Warren Sapp -- IN THE LINE OF FIRE ... At Florida Combat Range

Guns and pizza ... that's how Warren Sapp spent his Friday afternoon -- and TMZ Sports has photos of the former DT on the attack.

Sapp was part of a crew that hit up Combat City in Orlando, FL to shoot Airsoft pellet guns for his teenage son's birthday party.

We're told the Hall of Famer was quite the shot and darted around the place so fast, it was like he was back chasin' Brett Favre again.

Fun Fact -- one source at the combat zone tells us Sapp woofed down an entire pizza by himself right BEFORE he went into battle ... but we're also told he ran around so much, he probably burned the whole thing off.