0.7" seems a bit wide for a base and it would seem that the cartridge length is between 60mm & 65mm so maybe some Gründig variant? Seems a chamber cast is in order. The W stamp on the solid projectile tube is not a proofhouse stamp but a mechanic's stamp for compensation & liability for a mechanic like Wolf, etc. I guess the possibility exists for a M???

Kind Regards,

Raimey
rse