About the only thing that can be said about #7465 is that it has "test characteristics" but has a serial number higher than any in the Bannerman purchase. Numbers 7108 and 7147 were part of the Bannerman purchase and have the last two digits of the serial number on the left flat of the takedown lever, just like 7465. So it is "possibly a Test Luger" but we will never know. The farther out of the 71xx range you get the less likely the possibility.
P.S. I am a grandfather but far from a "grandmaster"
