i had an idea about adding recoil springs, because the cannon staying stationary after firing the shell feels a bit unnatural and it would look cool to have it move.

but to make it more realistic you can only use it on cannon barrels which are smaller than the barrel behind it, it might also help against Z-fighting since the cannon textures wont overlap.

my idea on how it will work is that the more springs you place, the further back it can go, but you have to add more powder charges or increase the amount of nitro powder in big cartridges to make it go further back (you could change how much is required to make the cannon move but it stays at 1 charge per block)
to do it you could right click on the side of a cannon to add or remove it.

Actually, you can use the CBC: Modern Warfare mod.