John, I'm not questioning wether copper was used , My question is, If copper was used why are we excluding it from being ABO? I personally don't care what people use to make there points, I like using all the tools. Antler, stone , copper even biscuits. I have tried ABO some and worked good on some materials and on others I struggled. I like trying to knapp every material that I can get my hands on so I guess I will be a copperhead for now 
Bob
The reason that people exclude copper from ABO is because they assume that copper was not used, and they assume that more natural flaking tools were used, such as wood, antler, ivory, stone, etc.
Beyond this, many knappers assume that ancient knappers simply invented techniques on a whim. And, so any use of certain materials, for flaking tools, is believed to be a potential candidate for a bonafide practice, especially if a person can get a flake, and a flake scar, that looks like a match.
This entire line of reasoning is totally flawed. There are way too many assumptions, and unsubstantiated beliefs, involved. It is much safer to take known flakers into account - or even make known flakers the starting point. To ignore the known evidence, and then come up with theories is a travesty.
That being said, Ishi switched to steel, for pressure flaking. And, there was a reason why he chose steel over antler. If a person looks at Ishi's choice of a pressure flaker, and then looks at the material he frequently worked, and the considers the reason he stated for using a steel pressure flaker, what becomes apparent is that the explanation that Cushing gave, during the 19th century, regarding materials and flakers, might just be more valid then people think. And, if a person considers the practice that Ishi exhibited, and the bulk of the explanations given by tribal-trained Cushing, then one would have to expand the possibilities, regarding tools like these. But, that would require taking into account far more aboriginal flintknapping criteria, that was never taken into account, by disconnected European researchers, who did not understand any flintknapping very well, much less Native American flintknapping. And, if the full gamut of criteria, regarding evidence of known/suspected flaking practices, is taken into account, then one would have to honestly admit that some of these tools might not be pressure flakers at all. That being said, at a certain point, it is sometimes quite difficult to discern when a flaking tool was used in one specific manner, or was used in two different modes, that are quite distinct from each other. In some cases, one would probably have to narrow it down, by looking at the type of stone that had been worked, with said tools. And, once again, this dovetails with the issue that Cushing raised, during the 19th century, when it seems he tried to help European academics better understand the subject.
