The Armaguerra Model 39 semi-auto RIFLE is a VARIANT on the Revelli system. I have the only one I know of in this country..... unless you have one of those, also! My rifle is serial number A-38; it is generally believed that only 100 or so were made, even though it was adopted as the STANDARD rifle to replace the Carcano!
With the Rifle, to get the Bolt fully forward, it is necessary to press the Trigger; the Bolt is only propelled PART-way forward by the Main Spring and chambers its Round by Inertia. Pressing the Trigger cocks and releases the pivoting internal Hammer to slam upward against the Breech Lock, which then trips the Firing Pin to go forward, slamming the Breech Block fully CLOSED (if it already were not). The Breech Block will go forward about a quarter of an inch when you do this.
This may not be your problem, but it might be a LEAD TO your problem.
Good Luck!
Hope this helps.