It's a new definition of "high" caliber weapon.

YouTube star "Do It With Dan" posted a video showing him flying in a Cessna and firing an MP5 submachine gun out of the window around 3000 feet down into the Gulf of Mexico off the coast of Clearwater.

The flight took off from Tampa's Peter O. Knight airport last month. At the beginning of the video, the YouTuber even asks, "What are the legalities of this?" The pilot responds, "I didn't really ask...I'm assuming it's ok."

Turns out according to Tampa Police spokesman Steve Hegarty who spoke with the department's attorneys, the pilot is right.

"I'm not aware of any law that was broken by this," Hegarty said.

The pilot is Mark Serbu. Serbu owns "Serbu Firearms." Serbu says he has been a pilot for 10 years and actually looked up the rules before he came up with the idea.

"It wasn't unsafe like some of the people are alleging out there because my own daughter's on the plane. Am I going to risk my daughter's life? No," Serbu said.

Serbu said he circled off the coast of Clearwater at different altitudes to make sure no boats were around for miles before firing the 9 mm rounds out of the window. He also says he chose the gun specifically because it's easy to control.

"A kid could shoot this and it's not going to be out of control," Serbu said.

To the people who might "freak-out" over the video Serbu says it's all about perspective.

"People have different realities. In my reality, everything revolves around guns. Obviously, I'm a gun designer, I own a gun company, guns are everywhere and to us, it's like if you're going to do something, hey, bring a gun along," Serbu said.

But that also can make you a target. The FAA says they are investigating to see if any Federal regulations were violated.