Your Enigma is obviously not a 4-wheel machine. The fourth wheel does not step. the 17576 key presses is irrelevant. What is significant is the 4-wheel M4 had 336 different wheel arrangements (wheel orders) compared with the 60 wheel orders of the 3-wheel Enigma. This made breaking much more difficult and Bombe runs incredibly slow, until the US navy 4 wheel Bombes were brought into service. In practice the basic wheel order was usually obtained from weather code breaks which use a 4-wheel machine set up to operate as a 3-wheel. Once this code was broken, it was only necessary to find the 4th wheel setting, the other settings being identical. M4 keying was also incredibly difficult to break, it used bigram tables,, this was done by Turing.