I inherited a 1920 Commercial, similar to the OPs. The exterior and bore were not in great shape, but otherwise it was tight and clean. I had it rebarreled, refinished, and a trigger job performed by a local Luger specialist, and I really enjoy occasionally shooting it. Last time was a grudge match against a buddy who has a '42 Mauser, his a John Martz restoration.
My gun is not really at all finicky, as far as function is concered, as long as the ammo is of sufficient power, and it fits in the magazine. I resize .311"-.312" bullets, and not all have the right shape, construction, or proper location of the cannelure.