The M6 Air Crew Survival Weapon was however mostly inadequate for anything else but to hunt small game for food in survival situations; hence, the USAF phased it out during the 1970s, leaving the pilots to carry only their service pistol.

But still, its undeniable appeal paired to the advantages it offered for some civilian purposes, and as the years went by, a few gunmakers distributed several commercial variants of the design – most notable of them being the M6 Scout, manufactured in Czech Republic for Springfield Armory and available on the U.S. market until 2007.

At the 2014 edition of the SHOT Show, the Italian-based Chiappa Firearms company first showcased its own takes on the famous M6 survival weapon design: two combination rifles – dubbed the M6-22 and the X-Caliber – being essentially the same gun with very little to tell them apart.

The M6 X-Caliber combination gun has a .22 rimfire bottom barrel, a 12-gauge smoothbore top barrel, and is issued with the X-Caliber Set of inserts. The M6-22 has a .22 rimfire bottom barrel, and alternatively a 12-gauge smoothbore top barrel compatible with the X-Caliber inserts, or a 20-gauge barrel.

Apart from the name and a slight outer resemblance, the original M6 Air Crew Survival Weapon and Chiappa's M6-22 and X-Caliber combination guns do not have much in common.

So to speak, the Chiappa guns are bulkier to withstand the use of higher calibers, and longer to meet the minimum overall and barrel length limits imposed in certain jurisdictions.

The make of the stock is one of those guns' most peculiar features: while its skeleton is made out of stamped steel, its body is essentially a sturdy and rigid polypropylene foam block, which absorbs recoil while keeping overall weight to a minimum (about 2,5 kilograms, or 6 lbs).

Do not expect to feel like handling a fine gun: the stock essential design - quite squared - makes it a little bit cumbersome, especially when firing the 12 gauge barrel, also because of the overall lightness of the gun.

The polypropylene stock has eight hollow seats to host five spare .22 rimfire rounds, two spare 12-gauge or 20-gauge shotshells, and the factory-issued cleaning kit.

The Chiappa M6-22 and X-Caliber over-and-under combination guns are fit with cold-hammer forged barrels with automatic extractors. The frame of both models is also manufactured out of steel. 

Just like the original M6 Air Crew Survival Weapon – and just like Chiappa's own Little Badger carbine – the M6-22 and X-Caliber combination guns fold in two for easier storage or transport; the break-open action is activated by a massive lever that also works as a trigger guard.

Breaking the guns open for loading will also automatically cock the internal hammers, which on the M6-22 and X-Caliber combination guns replace the selective external hammer found on the original M6 Air Crew Survival Weapon.

The two 47cm/18.5" barrels are cold hammer forged out of chromoly steel; the top smoothbore barrel comes with an integrated cylindric choke, while the bottom .22 Long Rifle caliber barrel has six right-handed grooves, and a 1-in-16" rifling twist.

The front sight of the Chiappa X-Caliber and M6-22 combination guns is fixed, and comes with a high-visibility fiber-optic insert.

The rear sight is adjustable for windage and elevation, manufactured out of polymer, and essentially a copy of the M1 Carbine's rear sight. It is basically the same rear sight found on Chiappa's M1-22 autoloader and – once again – the small but nonetheless highly successful Little Badger carbine.

Yet another feature that the M6-22 and the X-Caliber combination guns have in common with the Little Badger model is the triple MIL-STD 1913 Picatinny rail located on the frame, allowing the installation of optical sights or other useful accessories.

The Chiappa M6-22 and X-Caliber combination guns are now finally available on basically all civilian markets worldwide, but they were conceived with a special consideration for the U.S. market and its peculiarities.

Not only are those two small and versatile combination guns perfect for small-game hunt, leisure plinking, formal target practice, and as an entry-level guns to introduce the youngest to the basics of marksmanship and safe firearms handling; but their low weight, their compatibility with a plethora of different chamberings, and their capability to fit in a small backpack will make them a great choice for those outdoors enthusiasts who may want to carry a defensive tools against wild animals when camping or hiking in the wilds.