Can't help with a maker, as there are no maker's marks, but the gun was proofed to shoot 0.3 grams of NGP m/71 - that's Neues Gewehr Pulver - a fine rifle powder developed by the German Army of the time. The projectile is a 27.7gr bullet - 1.8grams. DRMS is a sub-variant of DGRM - the number along with it - 20792 - has been noted on numerous occasions on various types of gun and is said to a particular mnufacturer - I don't know who that might be.
You might find something like it in Tom Rowe's books 'Alte Scheibenwaffen' [old target-shooting weapons] - Vol III deals with handguns of this type, usually made by the likes of Tell and Puff.
Hope that is of some use.
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