in SPR the Company commander as the thompson and the sargeant has the carbine. Would most likely be the other way around as the carbine would be a good weapon for individual defense and company commanders were not normally being the first one in the hole like a thompson gunner would have been.

Anyway the marines were rather fond of that little carbine even if it was not effective at a distance. But it was light weight and easy to use in the dense jungle where you often did not engage the enemy until you were a few yards from each other.