That function is not attached to anything.
here:
function bulletexplosion (hitX, hitY, hitZ)
createExplosion ( hitX, hitY, hitZ, 2 )
end
addEventHandler("onPlayerLogin", root,
function ( _, acc )
local accName = getAccountName ( acc )
if isObjectInACLGroup ( "user." .. getPlayerName(source), aclGetGroup ( "FGMembers" ) ) then
addEvent("bulletboom",true)
addEventHandler("bulletboom",getRootElement(),bulletexplosion)
end
end
)
Of course client is needed.
Now the player must log in, and it will check if he's in FGMembers.