I would be a little reluctant to draw too many conclusions from an article that starts out with the title
"Lugar" Pistol Serial Number Ranges!

Note that there were 780 pistols in the Bannerman purchase, not 770 as the article states.
Also remember that 50 test pieces in good condition were swapped for the 50 Cartridge Counters. These 50 were turned over to a US distributor for disposition. They weren't included in the Bannerman purchase and there is no record of their serial numbers. But they are legitimate test pieces and they are in the mix.
Therefore, we have 220 not in the Bannerman purchase minus 50 swapped out, leaving us with 170 guns that were either lost, damaged beyond use, stolen or given away.