Sound to me like a bait and switch add. They get you into the store(bait) and then sell you a rifle at a higher price(switch). Ask for a rain check, if they refuse ask for the manager, ask why not. Then say that this sounds like a bait and switch add and that you are going to talk to the state attorney about filing a complaint.
I ran into something like this before, not for a rifle, I got a rain check and I got my item.