I have loved this AirGun design since buying the original version made in 1978 called the Crosman 1322 Medalist, and shooting it for over 25 years! The recently updated P1322 pneumatic pellet pistol plus the 1399 shoulder stock makes a compact, powerful & very accurate backpacker Carbine that only needs periodic maintenance with Pellgun oil, and a supply of .22 caliber AirGun ammunition as well as some elbow grease to pump up and charge the AirGun. The breach accepts any length, shape or size of .22 caliber pellet/slug/roundball. There are a few options for mounting optics that work well, but the best one I have bought was a 3D printed picatinny rail that is made to fit the 1322. You can upgrade these Crosman 13XX pneumatic airguns to your heart's delight, but be careful, before you know it, your $100 AirGun has $300+ worth of internal & external upgrades. Easily charge the AirGun with ten pumps of air, which is enough power to hit targets accurately from greater distances than lower powered AirGuns. This AirGun is basically as powerful as it gets for "un-regulated Firearms" here in Canada. Any power upgrade, even just a simple barrel change will increase the muzzle velocity enough for this AirGun to be classified as an "un-restricted Firearm" which will require a P.A.L here in Canada.