.12 Eichelberger Long Rifle
The .12 Eichelberger Long Rifle is a wildcat cartridge created by Bill Eichelberger in 1982 and was made for short to mid-range small game and target shooting. The cartridge is a .22 Long Rifle casing, necked down using a series of dies, to finally accept a .123 caliber projectile. It is one of the smallest wildcat cartridges to ever exist, with the exception of Bill Eichelberger's .10 Eichelberger Long Rifle, which he would later create in 1999.
Being a rimfire cartridge, it can basically only be fired once. As a result, the process of very carefully loading a custom power charge, necking down the case using a series of dies and annealing, trimming, and finally seating the tiny .123 caliber bullet becomes a significant task. As a result, it's largely a novelty.
As per the data provided in Frank Barnes' Cartridges of the World: The .12 Eichelberger Long Rifle contains a 10 grain bullet with 2.6 grains of AA9 powder. This reaches a velocity of 2,810 feet per second for 175 ft lbs of energy.
|Bullet (Grains)||Powder (Grains)||Velocity (FPS)||Energy (ft lbs)|
|10 Grain (.123 caliber)||2.6 Gr. AA9 Powder||2,810 fps||175 ft lbs energy|
Conversions, Custom Barrels, Projectiles
According to Frank Barnes' book series Cartridges of the World, the .12 Eichelberger Long Rifle "...works well with 22-inch barrels having a rifling twist of 1:5. Suitable actions to rebarrel and chamber for the .12 Eichelberger Long Rifle include modern .22 LR bolt actions, and single shots such as the Thompson/Center Contender and G2.
It appears that SSK Industries was supplying .12 barrels and appropriate projectiles for loading this cartridge on custom order basis, though it's unclear if they still offer these items after being acquired by Lehigh Defense.