WMA is the headstamp for the CASE for Winchester Military Ammunition
Doesn't mean who loaded the complete round.
I have factory Mk211 Raufoss rounds with a GREEK headstamp on the case! I guess .50 brass was in short supply that year.
Brown tip probably means the frangible, but could also mean the 77gr OTM rounds (knock off or own rolled Mk 262 rounds)