Mauser 27mm Gun

I didn't make out that the 27mm rounds were actually so big.

[UPDATE]The Mauser BK 27 is used in the Panavia Tornado, the Alpha Jet, the JAS 39 Gripen, and the Eurofighter Typhoon. At one time the USAF hoped to license its production for the F-35 Lightning II joint strike fighter, but those plans have apparently been cancelled in favour of the GAU-12.
Recently Rheinmetall developed also modified, remote controlled naval versions, the MN 27 GS and the MLG 27 fully automatic naval guns, applied on many ships of the German Navy. 87 MLGs 27 have been ordered by the German Navy so far. The Royal Netherlands Navy ordered 4 MLGs 27 for their new Offshore Patrol Vessels.[/UPDATE]