The Lewis Gun utilized by British and American forces weighed 13 kg and could be carried by just one soldier. The French Chauchat was even lighter at nine kg. Even though considerably less effective than heavy machine guns, these weapons gave the infantry an important source of mobile automatic hearth. https://machguns.com/product/lot-1450-auto-ordnance-a-range-1928-thompson-class-iii-nfa/