In the field at the start of the level, charge forward past the three MG42s in the windows and sandbag. This is best done under the easiest difficulty setting. Stand there without shooting anyone, and your men will waste themselves on the 42s. If this is done long enough and with "Insane body count", they will stop spawning all together. You can do the same thing almost everywhere else there is a 42 and spawning men.