Long Action
A rifle action sized for longer cartridges around the .30-06 length, needed when the case is too long for a short action.
A long action is sized to feed cartridges roughly as long as the .30-06 Springfield, with a longer magazine well and a longer bolt throw than a short action carries. Rounds with tall cases or long, heavy bullets seated well out need this extra room, so the receiver is built longer to give the cartridge a place to sit and the bolt a path to chamber it.
The trade is a little more weight and a longer stroke per shot compared with a short action. When a cartridge grows beyond even the standard long action length, as many belted rounds do, the rifle moves up to a magnum action built with still more room.