Re: value of 1916 Luger ?Officer? Gun??
I suspect that the barrel was replaced later, possibly in the U.S. It was pretty common, both in Germany and here, to number a replacement barrel to match the grip frame number, which is why GOOD pictures of the barrel number and grip frame number (the front of the grip frame).
FWIW, the Germans considered the master number to be the one in the front of the grip frame, just under the barrel. It is the number that has the suffix letter, if any. But the BATFE ruled that the receiver (the part the barrel screws into) is the gun because it can be fired by pressing on the sear without the grip frame being attached. But the receiver has only the number, not the suffix letter, so there is some confusion about which number is the correct one if they don't match. All the dealers I know record the grip frame number with suffix, plus the maker and date, since all that is needed for complete and unique identification.