Although current rimfire cartridges are all 22 or 17 caliber, many of the rimfire cartridges of historical significance were of larger caliber. One of the most important rimfire developments was the 44 Henry cartridge developed by B. Tyler Henry. It has the distinction of being the chambering for the first successful lever-action rifle. Imagine the effect of a few Union soldiers firing Henry lever-action rifles, which had tubular magazines that held 15 cartridges, on the Confederate soldiers who were using singleshot muzzle-loading rifles! Ballistics of the 44 Henry were not impressive by today’s standards (a 210-grain lead bullet propelled by a charge of 28 grains of black powder to give a velocity of 1,150 ft/sec), but the importance of rapid, sustained fire in military operations is obvious. The 44 Henry cartridge was in production from 1860 to 1934. Another large caliber rimfire cartridge used in the Civil War was the 56 Spencer. Incidentally, the Henry lever-action was produced from 1860-1866 and was no doubt a driving force which led to the development of the Winchester 73 which used the center fire 44-40 cartridge.
Several other rimfire cartridges were developed about the same time as the 44 Henry. As is now the case with 22 caliber cartridges having different lengths, larger caliber “short” and “long” rimfire cartridges were common in the latter half of the 1800s. Examples include the 30 Short and Long; the 32 Extra Short, Short, and Long; the 38 Extra Short, Short, and Long; and the 41 Short and Long among others. Revolvers were often designed with cylinders to accept the shorter cartridges while the extra long types were most often used in singleshot rifles. They were, of course, loaded with black powder. Although there is no need to review the development of all of these cartridges individually, it is necessary to mention several of them in order to trace the evolution of the rimfire cartridge design. It is interesting to note that of the approximately 75 rimfire cartridges that existed in the late 1800s, only about 10 remained in production after WW II.
Two cartridges that were developed somewhat later were the 25 Stevens Short and 25 Stevens Long (sometimes referred to as simply the 25 Stevens) that were introduced around 1900. These cartridges were produced until 1942, and they were popular in rifles like the Stevens single-shot models. Firing a 65- to 67-grain bullet that was driven at approximately 1,200 ft/sec by a charge of 11 grains of black powder, the 25 Stevens had a good reputation as a small game load. Compared to any of the 22 caliber rimfires, the larger diameter, heavier bullet of the 25 Stevens, which had a muzzle energy of approximately 208 ft lbs, dispatched many species more dependably. It would still be a useful cartridge, especially in a modern loading that would improve the ballistics.
It is easy to forget that rimfire cartridges were produced in shorter lengths for use in revolvers and longer versions for rifles in many calibers.
Note how the current 22 Short and Long Rifle have parallels in the 25 Short and Long cartridges of a century ago.
Propellants and Primers
As the quest for better ammunition continued, it was recognized that black powder left a residue that attracted moisture and led to corrosion. Barrel life of the firearm was nowhere near as long as it is today. In the late 1890s, a new type of propellant was developed by making use of an entirely different type of chemistry. When cotton is nitrated with a mixture of nitric and sulfuric acids, the product is known as nitrocellulose, and it burns very rapidly when ignited. Moreover, the combustion produces very little smoke so this propellant is known as “smokeless” powder. This book is not the place for a review of propellant technology, but it should be mentioned that the burning rate of nitrocellulose can be controlled to a great extent by the particle size. Therefore, it is possible to produce nitrocellulose and tailor it for use in cartridges having different sizes. Another development in propellant technology resulted in a type of powder known as double-base powder. This type of propellant makes use of nitrocellulose to which has been added a small percentage of nitroglycerin. In addition to varying the particle size of the propellant, various additives are included to impart particular properties such as flowing ease, reduction of static electricity, flash reduction, etc. By controlling these characteristics, a large number of types of propellants have been developed with burning rates that vary enormously. Some propellants work best in small cases such as the 22 Short or 25 ACP while others perform best in large cases such as the 300 Winchester Magnum.
Even with the use of smokeless powder, the problem of corrosion persisted. The cause was the residue that was produced from the primer that was a mixture that contained potassium chlorate. Because of the resulting corrosion, primers containing potassium chlorate became known as corrosive primers. Some ammunition was loaded with primers containing mercury fulminate and after detonation the resulting mercury reacted with the brass case which caused it to be weakened and thus unsuitable for reloading. In 1927, Remington introduced Kleanbore primers that contained a type of priming mixture that was noncorrosive. In most modern ammunition, the primer contains an explosive known as lead styphnate, but recently primers have been developed that do not contain lead. The motivation behind this is to reduce the amount of lead that is present in the air when firearms are used on indoor ranges. For use in rimfire cartridges, the priming mixture contains 35 to 45 percent lead styphnate, 25 to 35 percent barium nitrate, 18 to 22 pecent ground glass, and 6 to 10 percent lead thiocyanate as well as some other minor constituents. The function of the ground glass is to make the mixture more sensitive to friction when crushed in the rim. On the negative side, the small amount of ground glass remaining in the bore increases the rate of wear so that even though soft lead bullets are used, the bore eventually shows the effects of erosion. A 22 LR barrel will not last indefinitely. One of the characteristics of lead styphnate is that its explosive character is destroyed by oil and some organic solvents. If oil seeps into a case, it may cause the round to misfire. This is one reason for the substantial crimp given to 22 rimfire ammunition, the other being that a heavy crimp is necessary to give the correct “pull” that results in uniform velocities.
Remington ammunition has featured Kleanbore priming for many years as shown on these boxes of 22 LR cartridges from the 1950s.
Hyper-Velocity 22 Ammunition
Over the many years in which it has been produced, the 22 LR cartridge has undergone several changes. Most of these involved minor changes in velocity that resulted from the use of different powders or bullets of slightly different weight or shape. However, a radical departure from the norm occurred in 1977 when CCI introduced a round known as the Stinger. The new round utilized a 32-grain bullet that was driven by a heavier charge of powder that had a slower burning rate than the powder ordinarily used in 22 LR ammunition. To accommodate the larger powder charge, the case of the Stinger was made approximately one-tenth of an inch longer than the normal 22 LR case. The result was a round that produced a muzzle velocity of 1,640 ft/sec and a muzzle energy of 191 ft lbs. A flat trajectory resulted from the high bullet velocity so the effective range of the 22 rifle was increased. Owing to the high-velocity hollowpoint bullet, the new round was explosive in its effect on small pests or unopened cans of pop. The term “hyper-velocity” is generally applied to 22 LR ammunition that produces very high velocity.
Very soon after the Stinger was introduced, Winchester began producing a type of hyper-velocity round known as the Xpediter. This load utilized a 29-grain hollow-point bullet with a muzzle velocity of 1,680 ft/sec which gives a energy of 182 ft lbs. Federal followed suit by introducing the Spitfire which employed a 33-grain bullet with a velocity of 1,500 ft/sec and an energy of 165 ft lbs. The Winchester Xpediter was discontinued after being available for a few years, and the current Federal hyper-velocity load is not designated as the Spitfire although the ballistics are unchanged from that round.
Remington entered the competitive field of hypervelocity ammunition with two offerings. The Yellow Jacket features a 33-grain hollow-point bullet at 1,500 ft/sec giving a muzzle energy of 165 ft lbs while the Viper features a 36-grain truncated cone solid-point