The .22 Winchester Magnum Rimfire (WMR), often referred to simply as the ".22 Magnum," has been the most powerful rimfire cartridge on the market since it was introduced back in 1959. And, in terms of muzzle energy, it still is.

But there is a new leader in rimfire velocity, the .17 Hornady Magnum Rimfire (HMR). These two cartridges are based on the same case but use radically different bullets. Both were originally designed for use in rifles, and were quickly adapted to pistols. The single-action "convertible" revolver, supplied with two cylinders (.22 LR and .22 WMR or .17 M2 and .17 HMR), lets handgunners shoot two cartridges from the same pistol.

This comparison is a natural, as both cartridges are chambered in the same types of firearms and are used for small game hunting and short to medium range varmint shooting. For use in revolvers, the .22 WMR is probably the more versatile cartridge, as its heavier bullet hits harder at normal handgun ranges. But in the longer barrel of a rifle, the issue is in doubt. Which is the king of the rimfire rifle cartridges?

Winchester (Olin) designed an entirely new and larger case when they introduced their .22 Magnum. Unlike the previous .22 Long Rifle, the Magnum is based on a longer (1.052") and fatter (.241" tapering to .240") case with a rim diameter of .291". And the bullet is a full .224" diameter, like modern centerfire .22 bullets. In form, the .22 WMR case remains a straight sided, rimfire type with a cartridge overall length (COL) of approximately 1.350". The maximum chamber pressure is around 25,600 psi.

The new bullet weighed 40 grains, the same as the .22 LR bullet, but it was a true jacketed bullet, available in jacketed hollow point (JHP) and full metal jacket (FMJ) forms. .22 WMR bullets are generally of flat point or round nose shape, although Remington offers a Pointed Soft Point bullet. The original catalog muzzle velocity (MV) from a rifle barrel was 2000 fps, or 1550 fps from a pistol barrel. RWS still advertises a 40 grain bullet at a MV of 2020 fps and ME of 360 ft. lbs.

The major U.S. manufacturers have since reduced the catalog velocity of the 40 grain bullet to 1910 fps (rifle) and 1480 fps (pistol). CCI, Federal, Remington, and Winchester all load ammunition with 40 grain bullets to this standard.

Over the years, practically every manufacturer who loads rimfire ammunition has adopted the .22 WMR and different loads have been introduced. In the U.S., CCI, Federal, Remington, RWS, Winchester, and probably others offer .22 WMR ammunition.

The original 40 grain bullet weight is still the most popular. But we now have higher velocity loads using lighter bullets, such as the CCI Maxi-Mag +V and Federal V-Shok offerings that advertise a 30 grain Speer TNT-HP bullet at a MV of 2200 fps from a rifle barrel. ATK CORP owns Federal, CCI, and Speer. In addition to their 40 grain JHP and PSP bullets, Remington loads a 33 grain V-Max boat-tail bullet at a MV of 2000 fps. And Winchester now offers a 34 grain JHP at a MV of 2120 fps.

And there are also .22 WMR loads using heavier bullets. Examples would be the Federal Game-Shok load that uses a 50 grain bullet at a MV of 1652 fps, and the Winchester 45 grain DynaPoint bullet at a MV of 1550 fps. These are rifle velocities.

The .17 HMR was the result of a joint project involving Hornady, Marlin, and Ruger. It was introduced in 2002 and has become the most successful cartridge introduction since the .22 WMR. The initial sales of 17 HMR rifles were so strong that the demand for ammunition far outstripped supply for the first couple of years. Hornady was the first supplier of .17 HMR ammunition, but within two years CCI, Federal, and Remington all adopted the caliber.

The .17 HMR is based on the .22 WMR case necked down to accept .172" bullets. It is a bottleneck rimfire case about 1.060" long. The rim diameter remains .291". The chamber pressure and cartridge overall length are exactly the same as the .22 WMR, so any firearm that can be chambered for that cartridge can also be chambered for the .17 HMR. The success of the .17 HMR has been so overwhelming that most of them have been.

The original Hornady load drove a specially designed 17 grain V-Max bullet at a MV of 2550 fps and ME of 245 ft. lbs. This is a polymer-tipped, spire point, boat-tail bullet design. It is primarily a varmint bullet, designed to fragment in small animals and disintegrate if it hits a hard surface. In 2004 Hornady introduced a less destructive 20 grain XTP bullet at a MV of 2375 fps. This bullet is advertised as a controlled expansion, deeper penetrating bullet for small game and predator hunting.

Remington Premier brand .17 HMR ammunition also uses the Hornady V-Max bullet, with a gold plastic tip replacing Hornady's signature red plastic tip. Like the original Hornady load, the MV of the Remington Premier load is 2550 fps. And Federal loads the Hornady V-Max bullet, also at a MV of 2550 fps.

CCI and Federal introduced .17 HMR ammunition loaded with a 17 grain Speer TNT varmint bullet. This is a JHP spitzer bullet. Federal V-Shok ammunition claims a MV of 2550 fps, while the CCI version advertises a MV of 2500-2525 fps. In 2005, CCI announced a heavier 20 grain GamePoint controlled expansion bullet at a MV of 2375 fps.

Hornady's .17 HMR ammunition is loaded with great precision. It is intended to deliver 1 MOA or better groups at 100 yards. The other brands seem to have followed Hornady's lead in this matter. All of the .17 HMR ammunition that I have tested has proven to be very accurate.

We will compare the .17 HMR and .22 WMR in terms of velocity, energy, trajectory, sectional density, bullet frontal area, killing power, and accuracy. But first we have to decide what loads to compare. One of the "hottest" current .22 WMR loads is the Federal Premium V-Shok using a 30 grain Speer TNT-JHP bullet (load #P765). And, of course, the "standard" .22 WMR load uses a JHP or FMJ bullet at a MV of 1910 fps and is available from most manufacturers.

In .17 HMR, the 17 grain Hornady V-Max bullet is loaded to identical ballistics in the Federal, Hornady and Remington brands. These remain the fastest, flattest shooting .17 HMR loads. Heavier bullets with better SD have appeared, the Hornady 20 grain XTP bullet being perhaps the best known of these. So those are the four loads I propose to compare, 17 and 20 grain bullets in .17 HMR and 30 and 40 grain bullets in .22 WMR.

Since rimfire cases are not reloadable, there is no reloading data. In some instances this seriously limits the ballistic and bullet information available, as we shall see. The figures that follow were taken from the Federal, Hornady, and Remington ammunition catalogs.

Here are the velocity numbers in feet-per-second at the muzzle, 50 yards, 100 yards, 150 yards (when available), and 200 yards (when available):

• .17 HMR, 17 grain V-Max = MV 2550 fps, 2380 fps at 50 yards, 1900 fps at 100 yards, 1620 fps at 150 yards, 1378 fps at 200 yards.
• .17 HMR, 20 grain XTP = MV 2375 fps, 2051 fps at 50 yards, 1754 fps at 100 yards, 1492 at 150 yards, 1273 fps at 200 yards.
• .22 WMR, 30 grain TNT = MV 2200 fps, 1720 fps at 50 yards, 1340 fps at 100 yards, 1080 fps at 150 yards.
• .22 WMR, 40 grain JHP = MV 1910 fps, 1610 fps at 50 yards, 1350 fps at 100 yards.

From these numbers it becomes clear just how much faster the .17 HMR really is. At 100 yards the difference amounts to 550 fps between the highest velocity loads for each caliber! Clearly, the .17 HMR is the undisputed speed king.

Velocity is an important factor in calculating kinetic energy, but so is bullet weight. We have already seen that the .17 HMR is by far the faster cartridge, but the .22 WMR shoots a far heavier bullet. Energy is important because it powers bullet expansion and penetration, and is a major factor in killing power.

Here is the energy of our comparison loads, in foot-pounds at the muzzle, 50 yards, 100 yards, 150 yards (when available), and 200 yards (when available):

• .17 HMR, 17 grain V-Max = ME 245 ft. lbs., 185 ft. lbs. at 50 yards, 136 ft. lbs. at 100 yards, 99 ft. lbs. at 150 yards, 72 ft. lbs. at 200 yards.
• .17 HMR, 20 grain XTP = ME 250 ft. lbs., 187 ft. lbs. at 50 yards, 137 ft. lbs. at 100 yards, 99 ft. lbs. at 150 yards, 72 ft. lbs. at 200 yards.
• .22 WMR, 30 grain TNT = ME 325 ft. lbs., 200 ft. lbs. at 50 yards, 120 ft. lbs. at 100 yards, 80 ft. lbs. at 150 yards.
• .22 WMR, 40 grain JHP = ME 324 ft. lbs., 230 ft. lbs. at 50 yards, 162 ft. lbs. at 100 yards.

Here we see a different story. The .22 WMR starts with about a 75 ft. lb. advantage in kinetic energy at the muzzle. At 50 yards the 40 grain .22 bullet is carrying about 45 more ft. lbs., and at 100 yards the 40 grain .22 bullet still has a 25 ft. lb. advantage over the .17 bullets. At 150 yards the .17 HMR has an energy advantage of about 20 ft. lbs. over the 30 grain .22 bullet, and we have no figures for the 40 grain bullet beyond 100 yards.

What we can conclude from this is that the 40 grain .22 WMR load is the most powerful cartridge out to at least 100 yards, and beyond that adequate data is lacking. I would guess that the 40 grain .22 WMR bullet retains its energy advantage out to at least its maximum point blank range of about 125 yards.

Note that the energy of the 30 grain .22 bullet falls behind the 40 grain .22 bullet by 50 yards, and behind both .17 HMR loads by 100 yards. Also note that there is no practical difference in energy between the 17 and 20 grain .17 HMR bullets at any range.

High velocity has a big effect on trajectory, as does the ballistic coefficient of the bullet. Since the .17 HMR has the advantage in both areas, we can expect it to be the flatter shooting cartridge, and it is. Here are some factory figures based on a 100 yard zero and a line of sight 1.5" over bore (a scoped rifle):

• .17 HMR, 17 grain V-Max = +0.1" at 50 yards, 0 at 100 yards, -2.6" at 150 yards, -8.5" at 200 yards.
• .17 HMR, 20 grain XTP = +0.6" at 50 yards, 0 at 100 yards, -4.1" at 150 yards, -13.1" at 200 yards.
• .22 WMR, 30 grain TNT = +0.8" at 50 yards, 0 at 100 yards, -5.8" at 150 yards.

• .22 WMR, 40 grain JHP = +0.9" at 50 yards, 0 at 100 yards, -5.7" at 150 yards.

As expected, the .17 HMR shoots considerably flatter than the .22 WMR. Perhaps not expected is that the original 17 grain HMR and 40 grain WMR bullets outperform the newer bullet options in each caliber. Perhaps the technicians that designed these cartridges knew what they were doing!

Another way to zero a rifle is to take advantage of its maximum point blank range (MPBR). In the case of a small game and varmint bullet, I like to limit the maximum rise of the bullet above the line of sight to 1.5" to avoid shooting over small targets. The distance at which the bullet falls 1.5" below the line of sight then becomes the MPBR. Here is some MPBR trajectory data for the top load in each caliber based on a bullet BC of .123 for.17 HMR and .100 for the .22 WMR:

• .17 HMR, 17 grain = + 1.5" at 90 yards, 0 at 145 yards, - 1.5" at 165 yards.
• .22 WMR, 40 grain = +1.5" at 65 yards, 0 at 107 yards, -1.5" at 123 yards.

The 17 grain .17 HMR load confers about 40 additional yards of range on the varmint and small game hunter. That is probably the most dramatic practical difference between the two cartridges.

Sectional density (SD) is a bullet's weight divided by the square of its diameter. It is important because a bullet of greater SD will penetrate deeper, all other factors being equal.

Of course, varmint bullets such as the .17 caliber, 17 grain V-Max bullet and .22 caliber, 30 grain TNT bullet are designed to fragment on impact, destroying the maximum amount of tissue in the very shallow bodies of small animals, rather than to penetrate deeply into larger animals. For these bullets and their intended game, SD can practically be ignored, since penetration is not an issue. I know from experience that the 40 grain JHP bullet that Winchester loads in their .22 WMR hunting loads also expands violently in animals as small as tree squirrels. This JHP bullet features a large exposed lead tip as well as a hollow point. It is not a controlled expansion bullet.

The 20 grain XTP bullet for the .17 HMR is a controlled expansion design, and this bullet has a SD of .097, which is extremely low. The FMJ version of the 40 grain .22 bullet does not expand at all and would undoubtedly give the deepest penetration of all the bullets compared here. It has a SD of .114, which while better than the 20 grain .17 HMR bullet, is still not impressive. Consider, for comparison, that a 90 grain .243 bullet, the lightest bullet in the smallest caliber normally chosen for deer hunting, has a SD of .217.

So, while the .22 WMR has an advantage in SD over the .17 HMR, it is clear that both cartridges were primarily designed for shooting small animals where penetration is not much of an issue.

Bullet frontal area (cross sectional area) is important because it is a factor in the diameter of the wound channel it makes. Of course, if a bullet fragments immediately after impact, its frontal area in the conventional sense ceases to exist. This is exactly what the 17 grain HMR and 30 grain WMR bullets are designed to do, and fragmentation is typical of varmint bullets in general.

Bullet frontal area is important when considering a controlled expansion or FMJ bullet intended to penetrate deeply. The frontal area of a .172" bullet is only 0.0232". The frontal area of a .224" bullet is 0.0394". The .22 is small, but the .17 is tiny! Advantage .22 WMR.

Assuming a proper hit in the animal's vitals, killing power is determined by a complex of factors including (but not entirely limited to) the width and depth of the wound channel. This, in turn, is influenced by bullet energy, frontal area, sectional density, and expansion characteristics. In other words, it is a complicated matter that is still not entirely understood.

There have been many systems devised to compare the killing power of rifle cartridges, most of them by people with a pre-existing bias of one sort or another. The best and least biased of such systems of which I am aware is the Optimum Game Weight (OGW) formula devised by Edward A. Matunas and published in the Lyman 47th Reloading Handbook. Matunas tried to account for a variety of factors, not just caliber or kinetic energy or momentum, the major failing of most killing power formulas.

Like all such systems, OGW is not perfect. I find that it seems to be most reliable when dealing with mainstream centerfire rifle cartridges on the order of the .243 Winchester, .270 Winchester, .30-06, and .338 Win. Mag. Since we are dealing with much less powerful small bore cartridges in this comparison, I suggest that we view the following OGW information as a comparative tool, not as an absolute guide. That, in any case, is usually the best approach when dealing with killing power formulas.

The OGW figure estimates the optimum live weight of the animal for which the cartridge is best suited at any given range. Note that the OGW weight is not the biggest animal the cartridge will kill, merely the optimum size animal for that range. Also note that individual bullet performance is not a factor in calculating optimum game weight; it is assumed that the hunter will choose an appropriate bullet for the job at hand. And it is also assumed that the bullet will hit the heart/lung area of the animal; brain or spine shots would obviously result in much higher OGW numbers, but they are not considered. Here are our two best long range loads for OGW comparison:

• .17 HMR, 17 grain = 7 pounds at muzzle, 5 pounds at 50 yards, 3 pounds at 100 yards, 2 pounds at 150 yards, 1 pound at 200 yards.

• .22 WMR, 40 grain = 17 pounds at muzzle, 9 lbs. at 50 yards, 5 pounds at 100 yards, 3 pounds at 150 yards, 2 pounds at 200 yards.

The OGW figures indicate that the .22 WMR has superior potential killing power at all ranges. We could summarize by saying that the .22 WMR has about as much killing power at 100 yards as the .17 HMR does at 50 yards. Since its MPBR is limited to about 125 yards, the .22 WMR is probably the better choice for large varmints and small predators within the limit of its MPBR. Beyond the MPBR, accurate bullet placement becomes increasingly difficult as the range increases, and bullet placement is the most important factor in actual killing power.

Accuracy is not usually a factor in cartridge comparisons. Generally, two comparable rifle cartridges will deliver similar accuracy when loaded with equal care and fired in equally well-tuned rifles. The cartridge itself normally has little influence on the practical accuracy of hunting rifles.

But rimfire cartridges cannot be reloaded, so the quality control and manufacturing standards established by the ammo maker are of critical importance. I mention this simply because the standard of accuracy we have observed in the course of testing .17 HMR rifles and ammunition at Guns and Shooting Online is exceptionally high.

I know of no other rimfire hunting cartridge as accurate as the .17 HMR. We have consistently shot 1" or smaller 3-shot groups at 100 yards (sometimes much smaller) with off the shelf .17 HMR varmint rifles and ammunition loaded with Hornady 17 grain V-Max bullets. I'm talking about an average group size of less than 1 MOA. I find that to be extraordinary.

I have also owned and used enough .22 WMR rifles to know that they will seldom match that level of performance. I used to have a rather accurate Mossberg bolt action varmint rifle that would consistently shoot into about 1.5" at 100 yards if I did my part. That is as accurate as any .22 WMR rifle I have ever tested.

I am sure that the difference in accuracy observed between the two calibers is not due to the rifles, as many .22 WMR and .17 HMR rifles are actually the same models. I can only attribute the brilliant accuracy of the .17 HMR cartridge to the exceptionally high quality of factory loaded .17 HMR ammunition.

Of course, in one sense, the .22 WMR does not need to be as accurate as the .17 HMR. Remember that the .22 WMR has a MPBR of about 125 yards. If a given varmint has a 2" diameter vital area, a varmint rifle that shoots into 1.5 MOA is sufficiently accurate for its intended purpose within that MPBR.

A .17 HMR varmint rifle, on the other hand, with a MPBR of 165 yards, requires 1 MOA accuracy to stay in the vital area of the same size varmint at its maximum point blank range. In other words, due to its greater MPBR, a .17 HMR varmint rifle pretty much needs to shoot groups at 150 yards that are as small as those an acceptable .22 WMR varmint rifle shoots at 100 yards. The amazing thing is that they seem to do just that.

The .17 HMR and .22 WMR are both useful varmint and small game cartridges. Ammunition and rifles for both are widely distributed and commonly available. Recoil and muzzle blast are low for both, particularly from a rifle. They are good cartridges for use in semi-populated areas.

.17 HMR ammunition is generally more expensive than .22 WMR ammunition, but the difference will not be an unbearable burden to most small game and varmint hunters. For inexpensive practice at the range, neither is in the price class of the .22 Long Rifle.

Used with proper ammunition, the .17 HMR has an advantage in velocity, trajectory, and accuracy. The .22 WMR has an advantage in energy, bullet frontal area, sectional density, and consequently killing power.

After researching and writing this article, I have reached a conclusion about these two cartridges. I would favor the .22 WMR for shooting small game and varmints within 100 yards, and the .17 HMR if shots often run much beyond that distance.