do not think uncle mikes swivels , mauser rifles had QD sling attachments as far back as the Gew 88 if not older ,not always used but were available this looks like a old variant of them that uncle mikes sorta look like because the part that opens is smaller , i have some of the full size ones , UM added a screw feature , these look period , and i agree , first thing popped in my head was swede