Indeed, P. Oberhammer & the tubes should read something like P. Oberhammer Munchen Königl. Bayr. Hofbüchsenmacher or Kgl Hofbüchsenmacher, where he bought a Royal Appointment that requires a yearly fee.

I read it as 6,3X52R and a Repair date of July 1922/1928 where it was made in Zella - Mehlis and passed thru the Zella-Mehlis Proof Facility then.

Serbus,

Raimey
rse