i hate to say it but you wouldnt have the range.
but fear not, there is 2 things you can do:-
1) use power down shells - these have some sort of insert that reduces the FPS of the bb (recomended)
2) if its CO2 cartridge type, use a refilable cartridge from airsoft world, then either use a co2 recharger with co2 cartriges to fill it, or fill it with green gas