So after about six months of searching I finally found an Australian issue M9 bayonet for the collection. I probably paid a little too much for this one but I'm happy with the purchase. These are for the F88 Austeyr and M16 family of rifles and were made by Buck Knives in the US for an Australian contract. It has the broad arrow acceptance mark on both the blade and scabbard. Details are a little sketchy but apparently these were made in 1991 and only 20050 manufactured. Apart from the broad arrow marking they are identical to the commercial Buck M9 Bayonet. The Australian Defence Force now also use standard commercial Lancay and Ontario M9s which do not have any broad arrow markings which makes it almost impossible to tell if they are ADF issued items.
Two days after purchasing this one, I managed to find another broad arrow M9 from a retired Timor/Iraq/Afghanistan veteran. It is in used condition and I am probably going to sell it. PM me if anyone is interested. Interestingly the veteran also had a commercial Buck M9 which he stated was ADF issued to him. I'm unsure if the ADF purchased a large number of the commercial Buck M9s for issue or if a previous soldier purchased it privately to replace a lost / damaged bayonet without getting a bollocking.
Thanks for looking, any comments welcome.