When did Marina ever claim that? Not anywhere in your lengthy McMillan cut-and-paste.
You?re attempting to backpedal on a false claim.
Did she hear clicking or not? If not the rifle, what else?
That Oswald would be afraid of Marina seeing him handling/practicing/working the bolt action rifle is a part of the sarcasm meant in the OP.
That should be abundantly clear. Except to you crazed 'protect-Oswald-at-all-costs' fanatics hereabouts. After all, Oswald (AKA Dirty Harvey) can't be seen as anything but a 'he-man' superhero in CT lore, now can he John. No, not a guy who slept in the same bed and was bathed by his mommy well beyond the normal 'best-before' date for such activities.
However, there is good cause to suspect that Oswald would be reluctant to get-into-it again over the rifle with Marina, as amply demonstrated in my Macmillan cut & paste*
*@Newbies: You're welcome, in advance.