This rifle is an Amberg built Imperial German Gewehr 98 rifle that was acquired by Poland sometime after 1917. Rifles such as this were not necessarily 'battlefield pick-ups,' as many were simply left behind by German troops on their way home, or remained in barracks, depots and other facilities in cities and areas that were later ceded to Poland after WWI. A Polish Army inventory from 29 August 1922 accounted for 131,258 German Gewehr 98 rifles at that time. A later inventory in 1939 accounted for 241,000 of these, indicating that the post-war Polish Army augmented their post-WWI numbers with interwar purchases.
This rifle was then processed through Fabryki Broni at Radom, presumably for rebuilding to some extent. It was acquired by the Wehrmacht following the invasion of Poland in 1939, and received the types of upgrades seen on other modified Gewehr 98s. These included use of a K98k type of rear barrel band and the substitution of the 'Lange Visier' rear sight in favor of a flat tangent sight as seen on K98k rifles. The rifle shows the expected indications of WWII German depot work, such as 'X-ing' out or obliterating previous numbers and re-stamping new matching ones, characteristic bluing of the bolt components, use of armorer's parts, and stamping of depot stamps on the stock. This was 'duffle-cut' when I received it. For some reason, the front barrel band is the only part that doesn't match. All others are either originally stamped matching, or were re-stamped to match during rebuild at Berlin-Spandau.
All of the Polish-rebuild Gewehr 98's I've seen bear the F.B. Radom stamp, have a 'recumbent' Polish eagle stamped on the right side of the receiver, and are all prefixed with a newly stamped 'K,' as seen on the serial number on the left hand side of the receiver. It also appears that other, more recent looking numbers have been struck into the receiver, but I don't know if these were placed there during the Polish- or the Nazi-era rebuild. The yellow colored tint on the floor plate and butt plate are likely from oil or grease that has leaked into these areas and colored them over time.