Thanks for this reply, Eric. My understanding is that of the seven or so Oerter rifles that survive, two are numbered--one on the barrel, one elsewhere. Nos. 162 and 164.
With respect to Mr. Shumway, there is simply no easy way to move from these numbers--if they are production numbers--to even a rough guess at output of the shop--because we have no idea when the sequence began.
Did the sequence begin when Oerter took over the shop in 1766? When the shop was built in 1763? When Albrecht moved to Christiansbrunn in 1759? (That is, if this is a numbering system and at least 163 are unknown to us, we have no idea whether the numbering began with Oerter or with Albrecht.) Or when Oerter began to receive partial compensation for his work in 1771?
I know the last option--1771--has been favored, but it really makes no sense if you understand what changes really occurred in the Moravian economy at Christiansbrunn. In 1771, the economic arrangements at Christiansbrunn altered. Some brethren remained fully communal. Others became full wage laborers and had to pay for their food, clothing, housing, etc., just as everybody did in Bethlehem beginning in 1762. Others--and Oerter was in this group--received a lump sum each year (Oerter received £15, others got more or less) but still remained largely in the communal system: he did not have to pay for food, housing, etc. So there is no reason that, in 1771, Oerter would come to think of his work differently to the extent that he would sign his work. (And, of course, many unsigned rifles are attributed to him, so he certainly didn't start to sign his work consistently because he thought the work was "his" and not the church's.)
So I'm afraid that, to me at least, the numbering system remains mysterious. It's most likely that it is some sort of numbering system related to production, as Shumway posited. I don't have an alternate theory: I'm fishing about to see if others more clever than I can imagine another reason for these numbers.