Question about 30 round clips and bayonet lugs on Carbines in WW2

[USGI]

The whole pic doesn't make sence. There's this group on the left looking like they're in action, about four bottom right with weapons down and Thompson unloaded. There's four top right with hands in pockets disinterested and one lone guy eating. What I remember about enemy contact is everyone is interested and in some way involved. But the guy pointing his carbine? It DOES LOOK like a bayonet from here. But to me, the pic look like Korea too.

According to the caption on the photo:

American infantrymen chatting as they assemble & try out rifles they have chosen at hillside ammunition & supply station overlooking valley & the hills beyond on the Italian front in the Appennine Mountains.

To me, it looks like the guy aiming up the hill is holding a larger rifle - maybe it's not a carbine?