Late War Serial Numbering
There is much information about WW2 German weapons out there- much of it is in excellent reference books such as Hitler's Garands and Backbone of the Wehrmacht- however, these are only guides, and not everything in them is correct. Case in point is 1945 date K98k production numbers. It is widely recognized that Backbone of the Wehrmacht is incorrect in it's total production figures for 1945 manufactured 98k's. Below is the best I have seen it put into context: (information used with author Eric Davidson's permission, my additions in orange)
From Gunboards.com Mauser K98 Forum (member name Pisgah): (in regards to Backbone of the Wehrmacht production estimates for 1945 dated rifles) As they're estimates, they're all off to some extent. His numbers from 1945 are the farthest off of any of the years due to all of the changes which were instituted late war by the different manufacturers. Here are examples from 1945 including Law's estimates, and why they're wrong:
Mauser Oberndorf (byf/svw)
Law estimated 205,591 based on the known high svw 45 at the time being numbered 5593b. Law ignored svwMB production as many consider this code to be all French postwar manufactured. I think this belief is unlikely, but will deal with just byf 45 and svw 45 for the sake of comparison. The old KCN ran a serial number study for 1945 Mauser Oberndorfs in 1997. The high number found in that study for the no suffix block of byf 45 was 59,467. The high number a block svw 45 found was 16205a. The high number found for svw 45 in the b block was 5593b. So, actual production for byf 45 and svw 45 was less than 83,000. I say "less than" because some of the byf 45's and svw 45's were rejected by the Waffenamt inspectors and never completed during the war (despite having been assigned serial numbers) and were eventually completed by the French postwar. Law didn't account for the rejected rifles and didn't account for the fact that Mauser Oberndorf never completed any of the 5 digit number blocks of rifles (leading many to believe that the serial number blocks at Mauser Oberndorf corresponded to months of the year from 1943 until the end of the war).
Gustloff (bcd)
Law estimated 91,679 rifles based on the known high serial number of bcd 45 being 91679. The problem is that bcd 4's are known to exist with serial numbers all the way up to the 90 thousand range. When found with five digit serial numbers and in original condition, bcd 4's have late features--semi-Kriegsmodell, complete or partial phosphate finish, rougher machining marks, and fewer serial numbered parts. Based on the fact that these features didn't show up at any manufacturer until late 1944, it's pretty reasonable to assume that Gustloff mixed bcd 4 and bcd 45 receivers in their 1945 production. The best I can offer you with this code is a guess. I see 4-5 (or more) bcd 4's with the five digit serial number for every bcd 45 I see. Part of this is certainly due to the fact that collectors know bcd 45 is uncommon and don't sell them often. So, I would guess that the actual number of bcd 45's was around 20-25,000.
Steyr (bnz/swj)
Law estimated 196,625 bnz 45's and based this on the high known serial number for a bnz 45 being 5935t. The problem with this is that the high known serial number for bnz. 4 is 4917q and the low known serial number for bnz 45 is 4166q. This makes it look like Steyr had continuous numbering from 1944 on. So, likely the q block was a mix of bnz.4 and bnz 45 marked receivers. From what I have read, the final Steyr code (unknown at the time BBOTW was written) was swj XE, and known examples of this code are in the t block. So, a more realistic estimate of 1945 Steyr production would be 36,000.
Brünn I (dot/swp)
Law estimated 187,684 swp 45's produced based on the low known serial number of 43026a and a high of 87685a. The high known serial number of dot 1944 was 43125a. So the situation at Brünn I seems to resemble what I described at Gustloff. It looks like this factory had a surplus of dot 1944 marked receivers and used them when they started the five digit serial number pattern at the start of 1945. I have seen Russian capture swp 45's with serial numbers in the high 90 thousands of the a block, so based on this I would estimate production for the swp code being around 60,000
Brünn II (dou)
-Law estimated 29,712 rifles produced at Brünn II based on the high known serial number being 9079b. Since the Russian capture rifles have been imported since then, I have seen dou.45 serial numbers all the way into the f serial number block. Based on this, a more realistic estimate of dou.45 production would be 70,000.
Summation
So to sum it up for 1945:
1. Mauser Oberndorf (byf 45 and svw 45 only)= less than 83,000.
2. Brünn I (swp 45 only)= app. 60,000
3. Brünn II (dou)= app. 70,000
4. Steyr= app. 36,000
5. Gustloff (bcd 45 only)= app. 20-25,000
Notice that I believe that 1944 dated receivers were used in 1945 produced rifles at Brünn I and Gustloff and this is why I specified that my estimates were for rifles with 1945 dated receivers only instead of total production of rifles for that year. Quite a bit of overkill here in answering your question, but I have frequently alluded to Law's numbers being way off on this board, so took the opportunity to illustrate why.
This is a good analysis of 1945 serial numbers. One thing I will add (and this is a little speculation, and a little based on known facts)- For the production numbers presented, Steyr (bnz) is one of the rarest codes produced, yet seems to be the most prolific in the collecting community in matching, original condition, along with byf/svw Mauser Oberndorf. Inversely, dou and swp were made in greater numbers, but are hardest to find in any condition- this can be explained by geography. Most of the 45 date production of Brünn I and Brünn II were captured by the Russians during the war, and GI souvenir hunters were not able to loot those factories for guns. Steyr, Gustloff, and Mauser Oberndorf were both under allied control at the end of the war, and were "looted" by the captors- plus, anything left in the factories in the Allied zone was captured and later sold off as surplus, while in the Russian zone, the booty was captured and held as ready reserves for future wars, eventually to be refurbished. The factories in Czechoslovakia utilized leftover parts to build rifles for countries hungry for surplus "Nazi" weapons until the 50's, making for some interesting code/date combinations after the war, namely dot 1945 (it is not known if there were any dot 1945 rifles produced for the Nazi army- it is assumed by most that this is purely a post war code, however that is not confirmed- never say never).