There's a lot about this badge I don't like. The detail is not there, I've never seen a cliché badge with a screw-back, excess material on the top of the badge, etc., etc. Unfortunately these badges are amongst the most faked Imperial German items around.
Most people believe any stamped badge to be an actual issue piece. The silver ones were most likely all private purchase.
I don't believe the stamped pieces were made post-war, other than by numerous fakers. There's no shortage of fake stamped Prussian pilot badges, observer badges and gunner badges,
Hope this Helps, Rick