The dimensions of "long" and "short" actions vary with the manufacturer. At one time, for example, Remington made a Model 721 long action for .30-'06 size cartridges, and a Model 722 for .222 and .223 size. Now, there is one model number, 700, but it is still made in two action sizes.
Other makers use a "one size fits all" with the longer action adapted to short cartridges by means of magazine blocks and the like.
Some actions, especially ex-military Mausers, have been shortened by gunsmiths by cutting a piece out of the action and the bolt and welding the pieces back together. By cutting off center, some smiths made a long action and a short action from two standard length actions.