No, these are not casually gathered gun parts: that's the actual receiver of a quite rare gun that most collectors and even modern "experts" never heard about!
As you may see, the magazine is a cut-down FN FAL mag, which adamantly tells that the gun was originally chambered for the .308 Winchester caliber, a.k.a. 7.62x51mm. It was a semi-automatic carbine, manufactured in Italy in a very small quantity decades ago, and now out of production.
The rifle was originally conceived by a well-known American firearms engineer − mostly known for being the father of a famous small-sized sub-machine gun that first appeared in the 1960s − who was originally tasked to come out with a military-service carbine that would have possibly been adopted by an African Country. The weapon had to be easy to strip, maintain, and possibly to manufacture locally.
As a matter of fact, the project was based upon some very widely spread and available technical solutions and components from military rifles and carbines of that era: the bolt and the locking piece that holds the frame to the stock are patterned after the M1 carbine, while the cocking lever is pretty much akin to the M-14 rifle and the gas system is just the same as the one found on the M1 Garand rifle. The only original part was the idea of using the front sling swivel as a locking piece for the gas impingement tube: quite an odd, and possibly faulty, solution to come out with!
The manufacturing rights for civilian sales were picked up by an Italian company, which indeed started to produce it, albeit with the only minimum legal modifications to make it civilian-legal, and no other peculiar arrangements: this is what probably caused its demise. Such a small carbine would in fact have been aimed to the hunters' market, but its strictly military-oriented ergonomics hindered its success.
As a semi-automatic carbine, it would have been great for hunting hogs, most notably for battue hunting. But in that specific kind of hunting practice, it's absolutely paramount for a gun to be easy and fast to shoulder and aim. This carbine wasn't: it was manufactured only with the original military-type iron sights, with no provisions for optics: a big mistake, although red-dot sights were far away from becoming affordable and common back then. As a result, this carbine was made only in a handful of samples, now turned into highly sought after collectors' items.
But what was the name, and the manufacturer, for this quite unCOMmon carbine?