Hi Guys, New to posting photos so hope its worked, and new to drillings! Can anyone assist in identifying this caliber - I assume it's a 9mm

um, the picture didn't come through for me. Given when the Lewerentz drillings were made there's high probability it is the classic 9.3 X 72R. Be aware that there is at least 4 variations of that cartridge to include the Sauer which is a bottleneck cartridge. A chamber cast and comparison to dimensions is mandatory for the old German firearms.