Yes I've heard of Remo Popular but not Boker, happen to have one in a take-down.
Mine is a single shot model built on a 71 Mauser, not certain but some may have been built on the 71/84.
As stated there is a 98 Geha, 98 Hard Hit and a 98 Remo., which all came in 12, 16 and 20 gau.
Have yet to find a 20, must be quite scarce as are the 98 Remos in any gauge.
Have some pics, if someone will post. --- John303.