This rifle is actually hard to place in a category, as it spans the whole timeframe, from WW1 to WW2 Nazi!
Rather than bore you with a bunch of descriptions, I'll just post pics. Bolt handle is numbered 3147 but balance of bolt is numbered 42- a rework error I guess? Font looks the same! Note early "skeleton" style flat sight base. Also, handguard is E/359 inspected and numbered to match.
Looks like it went through a couple of reworks, Weimar Jt18 on the keel, Nazi Ws1 on the side. Barrel code and RR included in the photos for SimsonSuhl.