This is more of a guess on my part - I'm not sure what kind of real-life scope is in-game asset supposed to be modelled after. It doesn't look as any of the mass-fielded scopes used for FN FAL (eg. Hensoldt or Canadian C1 Sniper Scope), and as far as I know Australian armed forces never officially issued any.

However there exists a photo of Australian marksman in Vietnam, with an unidentified scope attached somewhat crudely to his rifle. Described as "2.75mm telescopic sight" (which probably means 2.75x maginfication) the scope indeed looks somewhat similiar to SOG:PF model - with a large bell in the back (occular), thin tube and windage turret on the right side of the weapon. SOG model (in it's current position) has large bell on the front (objective) and windage turret on the left side of the weapon - which also suggests that the orientation is incorrect, as most scopes will have windage turret on the right side.

Apart from that, the alternative (emergency) sight view for L1A1 scope is placed so that player sees the center of the occular, while (judging from other sniper scopes in game) it should be placed above the scope, allowing for "shotgun" style of aiming.