But patrol craft don't go very high... normally around 5000 feet, right? That shouldn't be much of a pressure issue, and being as it's patrol, the issue is more about flight range, right? This guy makes planes that can fly around the globe without refueling.
If you wanna talk high-altitude BB's... in the late 30's the Germans were supposed to have a rifle capable of shooting a sheet-metal piercing dart about 3/4 inch long and about as thick as a pencil-lead to altitudes of 40,000 feet. I wish I could remember what it was called...
