After more tests I found out there are more problems with this command on a dedicated server.
If "vehicle player setvehicleammodef 0" is executed by player who is driver of Hunter GMG then the player that is gunner will not see the effects of this command (for the gunner the magazines are still there but for driver they were removed by the command). If the gunner gets out of vehicle then back in gunner seat he will still see the magazines.