The rimfire ammo for sale is a type of firearm metallic cartridge whose primer is located within a hollow circumferential rim protruding from the base of its casing. When fired, the gun’s firing pin will strike and crush the rim against the edge of the barrel breech, sparking the primer compound within the rim, and in turn ignite the propellant within the case. Invented in 1845, by Louis-Nicolas Flobert, the first rimfire metallic cartridge was the .22 BB Cap (a.k.a. 6mm Flobert) cartridge, which consisted of a percussion cap with a bullet attached to the top.[1][2] While many other different cartridge priming methods have been tried since the 19th century, only rimfire and the later centerfire cartridges survive to the present day with regular usages. The .22 Long Rifle rimfire ammo for sale, introduced in 1887, is by far the most common ammunition in the world today in terms of units sold.

rimfire ammo for sale need to be made of pretty thin metal in order for the firing pin to be able to hit the rim hard enough to ignite the powder. If the casing was made of thicker metal, a firing pin hitting the rim would not have enough force to ignite the power.
The upside to using a thin metal for the casing is that rimfire ammo for sale is relatively inexpensive as compared to centerfire ammunition.
The downside to using a thin metal is that only small caliber ammunition can be made this way. Large caliber ammunition requires more powder to expel the bullet and a much larger case to hold the powder.
Consequently if thin metal was used in larger caliber ammunition, the casing would not be able to withstand the amount of pressure that a larger caliber cartridge requires and would blow apart.
Another upside of rimfire cartridges is they do not produce much recoil. Lower recoil can be a benefit if someone is new to shooting.