Hans M Gruny was a retailer of Schuetzen rifles made by gunsmiths that are not marked on the rifles. 
I have a 9.5x47R fully engraved Martini action rifle marked M Gruny Ingolstadt in gold lettering on the flat of scope rib of the barrel.  Also there is no markings on the barrel under the stock to indicate the gunsmith
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I've looked for further information on the Gruny and the results have been - NADA.  
The only indication of my rifles age is the caliber - 9.5x47R (0.374016").  It was designed in 1880 and became obsolete 20 years later. I found dies, brass and with the help of the ASSRA members, we determined the bullet and I had a mold made for it

Would be appreciative if you would post a picture of your rifle and identify the caliber plus barrel markings also ...

I'll get a pic from him, but the barrel marking of the "B" and the "U" are on there....Also, is with double trigger..Not sure what the caliber is..