I'm not a gun person at all but such things do interest me a bit. Markings indicate 25MM practice rounds w/tracers. That's why they are blue. From what I read Blue Bunnies are a brand name for large caliber handgun ammo and some other bullets. These remind me of the 22MM rounds used in the M61 Vulcan 6-barreled gatling cannon installed in A7 Navy light bombers (some other planes too). 100 rounds per second, over 10,000 rounds between jam/failure. That's theoretically 1hr40min of shoot-em-up time but not continuous firing as the things overheated pretty fast (as any gun firing that fast would, even with 6 barrels) so pilots didn't like using them for more than 1 second bursts a few seconds apart.