The 2A42, 2A38, 2A38M, and 2A72 fire percussion-primed ammunition; the naval and aerial cannons use electrical priming, and therefore their ammunition is not interchangeable with the land-based ammunition types, despite the same cartridge case size.
The 2A42, 2A38, 2A38M, and 2A72 fire percussion-initiated rounds; meanwhile, naval and aerial cannons utilize electrically-ignited projectiles, which cannot be swapped with the land-based ammunition types despite their identical cartridge cases.