I am not sure Rob. I do know that LT. Zacharias' knife was a crown stag. He was making so few knives at this point that there probably was not a rule established yet.

It's also worth noting that he converted to stacked leather by late 1942. So stag was in use for less that 6 months in the beginning of the fighter period. Later in the war there were a few stag handle knives made, but leather was the rule for sure.