
The higher 5 digit ones could have resulted from "drat, we are 50 pistols short and the contract is complete and if we open it up FN will charge us an arm and leg and take forever. The few 'E" prefix and refinished WWII German Hi=Powers could have been stop gaps, pending the arrival of the special contract or fill ins at a later point in time. (I have seen the Austrian ones with a two digit serial number.) Most of the ones I have seen have been under 10,000, which would tend to indicate a separate serial number range. It could also be (as you thought) that there was a special serial number range for the Austrian police Hi-Powers, with the few 'E' prefix, the few refinished WWII German ones, and the 5 digit ones being add ins.

It could be that there were various purchases of Hi-Powers at various times from regular production for the Austrian police.

I have, at times, completely reversed some of my beliefs when more info becomes available.
