The first response would be a fake as those are not standard markings .
HOWEVER , my Marine raider buddy has confirmed that several officers on Guadalcanal were carrying M60 semis while there .
I would love to see pictures and know the serial number of this .
I've had a M65 suppressed .22 used in the Pacific for years now , and I've had no luck verifying it's use there other than a couple of people's recollections .
Chris