What’s the meaning of “B”?
What’s the meaning of “B”?
At one time there were two 9 x 57 types ( two dimensional standards) , the model A and the model B.
The dimensional standardization of this caliber eliminated this distinction
Note that the “B” version ( which is the earliest type) is the closest to the standardized version, but not identical.
Here are some of my notes on the 9x57A &B types that help explain the differances (I wrote a complete article on this subject back in 2004):
Previously the 9x57 was considered to have been introduced by DWM (case #491A c1903/04) due to the fact that Mauser and DWM worked closely together and this was supposedly a ‘Mauser’ calibre. However, a 9x57 M88 was shown in the c1900 RWS/Utendoerffer catalog. Also, in a c1906 DWM factory drawing, the 9x57 Mauser (DWM case #491A) was listed as an “RWS model” which most likely implies that RWS introduced this calibre earlier than DWM. The exact date of introduction is unconfirmed. Rosenberger thought it was 1894.
What I believe is likely to have happened is the following:
In a development to get a larger calibre bullet in the M88 Mauser case, Utendoerffer/RWS first introduced 9mm versions of this case in both rimmed and rimless forms sometime in the 1894-1898 period. According to Rosenberger, the 9x57 appeared in 1894.
About 1903, when DWM was producing its own 9/9.3mm versions of the M88 case (see the case #491 series), it produced its own version of the RWS 9x57 cartridge (a c1906 DWM factory drawing shows the 9x57 as case #491A listed as an “RWS model”). However the DWM version had a significantly smaller shoulder diameter and therefore different shoulder profile (closer to the 9x57R case - M37) and this caused chambering problems. RWS recognised this problem and produced both case types. They referred to them as the ‘M88/9A’ with smaller diameter shoulder and the ‘M88/9B’ with wider shoulder.
Eventually this problem was rectified by ‘Normalising’ the case type sometime shortly before 1913. From this date, DWM just modified their case shape to match the new dimensions and continued to refer to it with the same case# (they did this with several other ‘Normalised’ cartridges incl 9.3x72R (EXP17). RWS and Geco continued to produce both A and B types at least until c1930. Note that in the 1911 Alfa catalog, all the RWS 9x57 cases are shown with the title “Mod 88 9mm A”. No “9mm B” are shown which is unusual.
The M88/9A has a narrower shoulder at 10.82mm, 2.5mm wide shoulder and 8.0mm neck length versus 10.95mm, 2.0mm, 8.5mm respectively for the M88/9B type. In addition the RWS drawing for the M99/9A has the comments “First made for the commission 21/1924” and also “Specially manufactured according to Karlsruhe sample cases”. Presumedly ‘Karlsruhe’ refers to the DWM Karlsruhe factory and this may imply that the “A” type was the type first produced by DWM c1903.
The “DM” hs style was still used after DM-K became DWM in 1896 (eg “D.M. 18 K 97” dated hs ). Note case #491A should be c1903 which is well after the 1896 formation of DWM.