Wouldn't blocks (or the things you put behind a tire to prevent it rolling back) not be used in cannons? I chose the period of U.S. Civil war to help narrow it down but I think it would apply to many cannons. If you wanted to fire artillery as quickly as possible, why not put some blocks behind the wheels to save time rolling it back to the original firing spot? I only ask because a U.S. Civil war game is adding artillery and there is no blocks present so you have to manually move the cannon forward to stay on target. Maybe they did use these and the game is wrong which seems likely. Thanks in advance.
There's little in the 1864 Field Manual about chocking wheels of field artillery, unless a piece has overturned. But the geometry of a gun carriage made chocking the wheels mostly unnecessary. It positions the cannon barrel rather high. The trunnions are forward of the center of gravity: more of the weight is at the breech end because the elevating screw or wedge is supposed to be able to lift or drop it. Altogether, that means that the recoil tends to lift the muzzle upwards and push the trail down into the ground. If more control was wanted, a rope could be wrapped around an upper felloe on one wheel, run across the top of the breech of the gun and tied to an upper felloe on the other wheel, so that when the wheels were turned the rope kept them from rotating far and forced the trail even more into the ground.
One other reason why they may not have been chocking the wheels is that a gun crew was expected to quickly move the gun around , in order to aim it. Chocks high enough to block the wheels likely would just make that more complicated.