The oldest cartridge still in production is the 22 Short. It has been in continuous production since 1857. The progenitor to this cartridge was the Flobert BB Cap, created in 1845. There are BB Caps made today that are different, but obvious descendants of this originating rimfire round.
There used to be 75 or more rimfire cartridges in production, from the lowly 22 short to the 56-56 Spencer and 58 Miller rounds. They ran the gambit: 22, 25, 30, 38, 41, 44, 50 calibers and more. The first successful metallic cartridges were rimfires. One of the first repeating rifles, the Henry used the 44 Henry round during the Civil War along with the Spencer rifle and its specific rounds.
One of the reasons more large caliber rimfires did not survive the end of the 1800's was the inability to reload them.
Oddly, the most economical rounds today are 22 LR, a rimfire. It would seem to me that it would make sense to make handguns and rifle today that fired modern rimfire cartridges. Most people do not reload and if the economical nature of the 22LR can be passed on to a357 or 45 rimfire, people would really go for it. Ammo is expensive these days and I think if we can offer a much cheaper route to shooting, hey... go for it.
Recently, several rinfire rounds have been introduced, the 17 HMR (based on the 22 Magnum necked down to 17 caliber) and the 17 Hornady Mach 2 (essentially a 22 lr necked down). Aguilar also offered their own 17 caliber rimfire round. Back in 1969, Remington offered the 5 mm Rimfire Magnum and Ilarco came out with the 22 Short Magnum Rimfire (a 22 Mag shortened to 22 LR length). Other then these, no rimfire round has been created since 1959 when the 22 Magnum was released.
In 1861 the 32 Long rimfire round was created. It was a black powder pistol round that offered ballistics that match today's 32 H&R Magnum. The 38 Long is a black powder round created in 1865 that exceeds 38 Special rounds from today, and the 357 Magnum of today is matched nu the 1870 black powder rimfire 38 Extra Long. The 44 Extra Long rimfire round was created in the early 1870's and matches pretty well with modern 44 Magnum rounds.
If black powder rounds from 140 years ago to match our modern centerfire rounds, why not make modern rimfire cartridges in larger calibers today?
