It does look like a middleweight, with tires that are 26" diameter by 1.75" (nominal) wide, but it's hard to be sure from a picture. And Schwinn used rims with a different bead seat diameter for their middleweights, but I believe AMF used the same size rims for both types. I don't know about Columbia.
May be an unequipped "Rambler" (#9621) since it has the badge. I see the 3-sided non flat rims, and color may be faded flamboyant red. Fenders seem non originals. Got this '65 catalog "cut" from Zaz Von Schwinn's Flicker album, for reference. Check serial# at rear non drive side (my wife's) and that is about it... Love'em Columbias but seems info is not readily available after Mr. Columbia's site ending. Would like to see a more organized group. Include partial serial number list screen shot prior to site's "kaput".