It helps. Full auto heats up quick and fins provide more surface area for dissipation of heat. Should really do short bursts but who doesn't want to play (DC Comic) Sergeant Rock?
...yes, we had cooling ''fins'' on our 81mm mortars...but I don't see them on many other hand held MGS? ...I remember one of our Marines ''ruined'' an M16 firing blanks on full auto--but these were old and much used M16s
Finns are an extra machining step. Costs more in time and money. Better to train the gunner to fire in bursts and to swap out the barrel when hot. The Jap. Type 92 heavy MG also had fins.
good call ..maybe I posted it somewhere else, but I read where the Aussies liked the Owen better than the Tommy
read that gravity is our friend, thats why mag is on top...works well with other top feed mg's. the owen was unique(?) in that it had a "garbage chute", where debris was channeled out. yes, read where some who were issued thompsons -traded by hook or crook- for an owen. the tommy was a masterpiece, the .45 deadly, but - the owen always worked. the AK of sub machine guns.