Here are some notes on the 8x63 RWS (M34) which is a very similar (and possibly related) cartridge.
************************************8x63 RWS (c1914)
This scarce experimental RWS sporting cartridge is only known from a small amount of specimens in existence. These all look factory loaded with SP bullet and have the early “R.W.S. N.” hs. Interestingly no RWS factory drawing of this case type is known to exist and it was not listed in any known RWS catalog.
This case was probably developed from either 30-06 or 9x63 M88 cases (M38). Note that this cartridge uses the smaller diameter 8mm bullet and not the “S” type 8.2mm caliber.
Probably intended as an extension of the M88 63mm case length types These M88 based 63mm cases included the 6.5x63 Neuber (A57) and 9x63 Hessmer (M38), both introduced prior to WW1 and also the 7x63 Jurgens Mauser (W34) which was produced well after WW1 in 1929.
This is not the same as the 8x63 Swedish MG case which has a c 12.5mm base. Nor is it a necked down version of either the 9.3x63 (M56) or 10.75x63 (M57) which were both “G Mauser” types, rather than M88 types and used a similar 12.5mm base case. There is a similar rimmed version apparently made by RWS (see M81) but that case has a lower shoulder and is more like a necked down 9x63R (M39).
This cWW1 cartridge looks like the fore-runner of the 8x63 Brevex in the 1950’s and the 8mm-06 of the same period which are all based on the 30-06 case necked up to 8mm (see images). The “BV 8x63” may well have been an attempt at a modification of surplus 30-06 rifles in France to get around the French regulations after WW2 about not being able to use military calibers. The rifle modification should have just needed a re-bore and new rifling rather than a complete re-barrel.
Here is info on the 3 very similar 8x63 based on the 30-06 case. Probably produced for different markets and purposes. Information is mainly from the ECRA Data Viewer:
++++++++++++++++++++Also some info on Brevex
ETABLISSEMENTS BREVEX of Suresnes, France operated from 1948 till 1959. This company was often just referred to as ‘Brevex’. It was founded in 1948 by Ingr. Polonski, a Polish Engineer. The suicide of Polonski in 1959 resulted in the company closing.
Brevex was best known for its “Mauser Magnum” actions, produced from reworked Mauser M98 Rifles, most of which were exported to the USA. BREVEX SURESNES was the tradename used on these Brevex actions on rifles made in France and imported by Tradewinds.
Due to ammunition shortages after WW2, Brevex also produced very limited amounts of sporting ammunition from reworked military brass. Initially in the late 1940’s, he just overstamped the cases (see 8x60S) but later machined the head first before stamping a standard “BV” hs with caliber. These stamps were generally poor quality. It produced very small amounts of the commoner European calibers such as:
7x57 Mauser (M46)
7x64 Brenneke (W5)
8x56 MS (A48)
8x57J Mauser (M7)
8x57JS Mauser (M32)
9x57 Mauser (M36)
9.3x62 Mauser (M54)
Also the more unusual 8x63 for sporting purposes (see M34) made from 30-06 cases and 270 Winchester - may have shorter neck?
Most cartridges had either coloured red or grey/black primers and were packed in green/white 10 round packets (see images).