It's not a "speculative theory". Oswald (allegedly) told Fritz that he brought a sack with his lunch.
But whether that's true or not, how do you get from "not a lunch" to "rifle"?
So Lee Harvey Oswald told Captain Will Fritz that the bag he carried contained his lunch!!! Why would you accept an accused assassin's statement compared to two (2) witnesses who are not concerned about execution in the electric chair?
Oswald's alleged statement should be compared to those of witnesses who saw the long paper-sack he carried at Irving and Dallas.
Frazier asked Oswald (at Irving) what was in the sack. Oswald said it was "the" curtain rods.
Frazier said that Oswald carried the paper-sack (at Dallas) with the lower part in the palm of his hand and the upper part under his armpit. That's too long for a lunch "sack" unless it contained french bread and celery stalks.
Aren't you one of the "researchers" who accepts Randle's and Frazier's "estimates" that the paper-sack (that Oswald carried) was 2 feet long give or take a few inches? Can that possibly be a sack that contained "lunch"?
John: Less polite members of the forum (than me) might call you a contrarian.