From Agent James Hosty's contemporaneous notes taken during Mr Oswald's first interrogation (which started 3:15pm, 11/22)-------------

Like most people, I long assumed Mr Oswald talked merely about a rifle which he had seen (and which, it was later established, belonged to Mr Warren Caster), rather than any particular rifle. However, I was knocked for six when I recently came across this FBI interview report for Mr Roy Truly from 11/22-----------

"the rifle"
Did Captain Fritz confront Mr Oswald with the Carcano, and did Mr Oswald claim he had seen Mr Truly with it two days ago?
The problem with that scenario is that Lt Carl Day said he locked the Carcano away in an evidence box in the Identification Bureau at around 2pm, returned to the Depository around 2:45pm, and didn't unlock the evidence box again until around 7pm that evening. It is hard to see how Captain Fritz could have shown Mr Oswald the Carcano during that first interrogation session......
Given that the first Caster rifle mentioned in the Truly interview report above ("a ___________ rifle") was in fact a Mauser, I think it's fair to ask: Was Mr Oswald shown a Mauser rifle during that first interrogation?

So!
------------Mr Oswald is shown
the rifle and says he saw Mr Truly holding it (or one just like it) two days ago
------------Mr Truly confirms that he held a deer hunting "_________________ rifle" belonging to Mr Warren Caster
------------Mr Caster confirms the story and fills in the missing part: "a .30-06 sporterized Mauser"
------------Mr Arnold Rowland sees a rifle in the hands of a man on the sixth floor some 15 minutes before the assassination and says it looks like "a 30-odd (aught) size 6, a deer rifle with a fairly large or powerful scope"
------------For the first hours after the assassination, all DPD tell the world about is a Mauser rifle found at the scene of the crime
Interesting!