It if rifle parts were wrapped up in a plastic garbage bag or some plastic wrap that Oswald could have found at Paines residence and inserted into the paper bag which is used simply as a cover so making the package less suspicious looking
Then maybe it might explain one end of bag being not sealed with tape
Still seems a bit illogical though, imo not to seal both ends just be on safe side, since 8lbs of mass wrapped in low friction plastic wrap might iadvertantly slide out especially if gripping package only at the top with one hand as Frazier’s sister observed Oswald carrying it