"Come on" meaning exactly that against a moving tank-sized target 800 meters is a HUGE distance for even a "bipod-equipped" light RPG (however heavy recoilless rifles on tripods or other heavy mounts can cope with these distances). As the game can´t distinguish between moving and stationary targets, RPG-16D has too long range game-wise, as it is used mostly against moving point targets, like vehicles. The M72 LAW has max range against stationary targets of 300 meters and moving 150 meters. And it is given a general range of 3 or 4 hexes in the game. So maybe the dropping down to 10 hexes for RPG-16D might be a good idea (it´s still 500 meters).
