There are photos of Mussolini surrounded by his elite black garbed body guards.....Their model 91/38 carcanos are equipped with black leather carrying straps that are very similar to the strap on the TSBD carcano. Whoever created the strap on the carcano wanted the rifle to look like a Guardie del Duce rifle. (Perhaps that person wanted to display it as a war souvenir and brag that he'd retrieved it from the body of one of Mussolini's body guards.) Since General Walker had led troops in Italy during WWII, such a war trophy would have been fitting with his character...... And yes, I'm suggesting that the TSBD rifle could have been provided by Walker.
So the conspirators stole his rifle from the garage (without being seen) and used it to murder JFK and frame Oswald (without being seen). Occam's razor is taking a beating in this forum.
Who says that Carcano rifle was ever in that garage to begin with?
Marina did John: http://www.aarclibrary.org/publib/jfk/wc/wcvols/wh1/html/WC_Vol1_0019b.htm
You're obviously not aware but Oswald didn't have a computer or the internet and eBay didn't exist till decades later.JohnM