The military has sold off millions of Garands through the CMP over the years I wouldn’t be surprised if they straight up don’t have enough for this.
Russians plan something very exciting to commemorate the Siege of Berlin 80th anniversary
They won't even cosplay as marines, just normal army grunts, of American forces in D-day there was 15000 airborne and 58000 infantry soldiers.
The funniest possibility is if the landing boats didn't work so they have to scrap the whole idea