The Gun Digest Book of .22 Rimfire. James E. House
ft/sec for an energy of 159 ft lbs. Aguila produces one other hyper-velocity round, and it drives a 30-grain bullet at an advertised velocity of 1,750 ft/sec to give 204 ft lbs of energy. However, the energy drops to only 93 ft lbs at a range of 100 yards. Another hyper-velocity round is the CCI Quik-Shok which uses a 32-grain bullet, but the bullet is designed so that it breaks into four pieces on impact. This produces a devastating effect on small varmints although penetration is generally less than with other types of ammunition.
Although the hyper-velocity ammunition gives dramatic effects at short ranges, the light bullets lose velocity more rapidly than do the heavier bullets used in conventional 22 LR ammunition. The result is that the remaining energy of the hyper-velocity ammunition is approximately equal to that of the slower rounds at a range of 100 yards or so. It is also generally true that hyper-velocity ammunition does not deliver the best accuracy in most rifles. There have been many reports published to verify that conclusion, and based on the results of tests conducted during this work it certainly true. Moreover, the longer cases of the Stinger and Quik-Shok pose a problem when used in rifles with so-called matchtype chambers because the case engages the rifling just in front of the chamber. With match chambers, the rifling extends back to the front end of the chamber so the bullet engages the rifling as a round is chambered. The makers of some rifles having match chambers warn against using the Stinger ammunition in those rifles. Bullet diameter for the 22 Short, Long, and Long Rifle is 0.223 inch.
With all of these developments and those described in the following sections, there can be little doubt that this is an exciting time for the rimfire shooter. More details on the performance of today’s rimfire cartridges will be presented in several later chapters in this book.
22 Winchester Magnum Rimfire (WMR)
As wonderful as the 22 LR is, there are situations where more power is called for. In 1959, Winchester responded to that need by developing a cartridge that utilizes a case that is 1.05 inches in length and has a slightly larger diameter head and body than the 22 LR case (0.291” vs. 0.275” and 0.241” vs. 0.225”, respectively ) . Instead of using a bullet with a heel of smaller diameter that fits inside the case and a bullet that has the same diameter as the case, the new round used a 40-grain jacketed bullet of 0.224-inch diameter. This “magnum” rimfire is appropriately named the 22 Winchester Magnum Rimfire (WMR), and the advertised velocity is 1,910 ft/sec from a 24-inch barrel. With a muzzle energy of 310 ft lbs, the 22 WMR is still the most powerful rimfire cartridge available. From the 20-inch barrel of my Ruger 77/22M, the velocity at 10 feet from the muzzle is below the advertised value by about 75 ft/sec.
The main drawback to the 22 WMR has always been the cost of ammunition. Although some special target ammunition in 22 LR may cost as much as $10 for a box containing 50 rounds, the cost of most of the ordinary types is only $2 to $3 per box. Some promotional ammunition in 22 LR can be bought for around $1 per box. Most of the types of ammunition in 22 WMR sell for $6.00 or more with the Remington Premier selling for around $10 per box. It is simply a fact of life that it costs around 12 to 20 cents per shot to fire a 22 WMR.
Three magnum rimfire cartridges are (left to right) the 17 HMR, the 5mm Remington, and 22 WMR. The 5mm Remington has been discontinued since the 1970s.
Being a larger and more powerful cartridge than the 22 LR, the 22 WMR could not be adapted to most actions that were designed specifically for the smaller cartridge. The actions had to be made slightly longer than those used on regular 22s, but very soon after the 22 WMR was introduced a large number of arms were available to chamber it. Winchester marketed the lever-action Model 9422M, and Ruger offered single-action revolvers with two cylinders, one in 22 LR and the other for the 22 WMR. Marlin, Savage, Anschutz, and others produced bolt-action rifles for the 22 WMR soon after its introduction. Currently, bolt-actions, lever-actions, and autoloaders are available in the magnum rimfire calibers as are many handguns (see Chapters 3 and 4).
The major complaint about the 22 WMR has centered on the subject of accuracy. It is popularly believed that the 22 WMR does not give accuracy that is quite the equal of that given by the 22 LR and some newer rimfire rounds. This perception may be in error, but that topic will be addressed more fully in later chapters.
5mm Remington Magnum
In 1970, Remington unveiled a rimfire magnum cartridge that offered even better performance than the 22 WMR. However, that cartridge deviated from the usual rimfire caliber because it was a 5mm or 20-caliber (actual bullet diameter is 0.2045”). The 5mm Remington Magnum cartridge produced 2,100 ft/sec with a ballistically efficient 38-grain bullet. As a result, the muzzle energy was 372 ft lbs, and the remaining energy also exceeded that of the 22 WMR at longer ranges. The 5mm Remington used a case that is slightly larger in diameter than that of the 22 WMR. Remington produced the Model 591 (box magazine) and Model 592 (tubular magazine) boltactions, but these were the only rifles produced for the 5mm Remington cartridge. Thompson/Center produced barrels chambered for the 5mm Remington to be used on the single shot pistols that they market. The 591 and 592 were discontinued in 1974 with a total of approximately 50,000 having been produced. The 5mm cartridges have become highly collectible with prices for a full box often being in the $50 to $75 range or more.
With greater energy and flatter trajectory than the 22 WMR, the 5mm Remington may well have been the best rimfire cartridge in modern times. Although the trajectory is not quite as flat as that of the 17 HMR with a 17-grain bullet, the 5mm Remington with its 38-grain bullet is a far more powerful cartridge. Part of the difficulty with the 5mm stemmed from the high pressure, which may have been as high as 35,000 lb/in2. The high pressure caused the case to expand into the extractor notches, which necessitated some changes in the chamber, bolt face, and extractor grooves. Given the propellants available today, it is likely that the remarkable ballistics of the 5mm Remington could be produced with a somewhat lower pressure. Moreover, there are several rifles available today that could probably serve as platforms for the excellent 5mm Remington cartridge. The Ruger 77/22M, Anschutz, Remington 504, CZ 452, and Kimber models come to mind immediately. We can only hope that rifles and ammunition in this outstanding rimfire caliber become available once again. If not, a 20-caliber cartridge based on a necked down 22 WMR case but utilizing the superb Hornady V-Max polymer tipped bullets would be very interesting and useful. Given the fine rifles that are available in 22 WMR caliber, it should be a simple matter to produce a 20 caliber cartridge based on that case.
17 Hornady Magnum Rimfire (HMR)
Perhaps no other new cartridge has generated so many printed words in such a short time by so many writers as the 17 HMR. Introduced in 2002, the 17 HMR was the first new rimfire cartridge since the short-lived 5mm Remington. However, the 17 HMR certainly will not suffer a similar fate! The number of rifles and handguns available in 17 HMR caliber is very large. This is natural because the 17 HMR case is simply a 22 WMR case necked down to hold a 17-caliber bullet. Therefore, a firearm designed around the 22 WMR can be made into a 17 HMR simply by changing the barrel. Even the magazines that hold 22 WMR cartridges will feed 17 HMR cartridges. Because so many firearms in 22 WMR caliber were already in production, there are now many that are also produced in 17 HMR.
Nominal bullet diameter for the 17 HMR is 0.172”. The original load consisted of a 17-grain Hornady V-Max polymer tipped bullet that was loaded to a velocity of 2,550 ft/sec giving an energy of 245 ft lbs. The well-shaped bullet has a ballistic coefficient of 0.125 so it holds velocity well which results in a rather flat trajectory that makes hits on small pests possible out to 150 yards or more. Although many larger varmints have been taken with the 17 HMR, the cartridge is at its best when used on species like ground squirrels, crows, pigeons, and prairie dogs. Early reports by some writers described the use of the 17 HMR on species as large as coyotes, but many reports have also described failures of the tiny bullets on larger pests like groundhogs, foxes, and coyotes. One of the most interesting discussions on the 17 HMR is that by C. Rodney James which was published in Gun Digest 2005. In an article published in the February 2005 issue of Predator Xtreme, Ralph Lermayer has related some of his experiences on the failure of the 17 HMR as a cartridge for use on larger varmints. Recently, loads employing 20-grain