If you don't have patience to go all the way to 55 level in Call of Duty 4, here is some kind of a patch that will do it for you. I don't recommend use of level hack as you may not try all the weapons if you skip them. The best thing is to try all levels and pass them correctly. Anyway you may change something like a key code and if you lose your previous levels this may help. Here is download link - Level 55.