I just looked at the ser # it is 61 engraved on trigger guard so may be a very early Linder gun with out stampings I was wondering why so little stampings and no proof marks now I am thinking this is a very early Linder there is an other stamp on the barrels but is so small looks like typewriter keys even with a 10 power loup I can not make it out the quality is poor compaired to the other stamps on the gun. I will steel wool it tomorrow and see if I can make it out it is so small hard to see it is stamped.