Understanding the Cartridges: .17 HMR vs. .22 WMR
The Rise of the .17 HMR
The .17 Hornady Magnum Rimfire (.17 HMR) is a relatively new addition to the rimfire family, born out of a collaboration between Hornady and Sturm, Ruger. Introduced at the turn of the millennium, the primary goal of .17 HMR was to provide a high-velocity, flat-shooting cartridge that could excel in varmint hunting and target shooting. It essentially took the existing .22 WMR case and necked it down to accept a much smaller .17-inch bullet. This innovation allowed for significantly higher muzzle velocities, leading to flatter trajectories, reduced wind drift, and increased effective range. The .17 HMR quickly gained popularity among hunters targeting small game, such as prairie dogs, squirrels, and rabbits, and is a favorite among target shooters.
The Reign of the .22 WMR
The .22 Winchester Magnum Rimfire (.22 WMR), often referred to as the .22 Mag, is a true classic in the rimfire world. It has a longer history than the .17 HMR, introduced in the mid-1950s by Winchester. The .22 WMR was designed to provide a significant step up in power compared to the standard .22 Long Rifle (.22 LR). It was initially intended for use in lever-action rifles, and it quickly found its place in the hands of hunters and target shooters who needed more range and striking power than the .22 LR could offer. Its popularity has endured due to its effectiveness in hunting small game and its suitability for plinking and recreational shooting.
Key Differences: A Closer Look
While both the .17 HMR and .22 WMR are rimfire cartridges, and outwardly they share a similar look, the critical differences are what make them incompatible. These variations are fundamental to the safety of your firearm and the shooter.
The most significant difference between these two rounds lies in the bullet diameter. The .17 HMR uses a .172-inch bullet, while the .22 WMR utilizes a .224-inch bullet. This difference, seemingly small, is the primary reason why you cannot interchange these cartridges. Your .22 WMR firearm’s barrel is designed to safely contain a .224-inch bullet. Attempting to fire a smaller .172-inch bullet can lead to disastrous consequences.
Although the cartridges use the same base, the .17 HMR case is technically the same as a .22 WMR, the bullets are not. Some firearms are picky about headspacing, or how the casing sits within the chamber. .17 HMR cartridges and .22 WMR cartridges may be so close in dimensions that there is little or no margin for error.
Another crucial difference to be aware of is the pressure each cartridge generates. While both operate at relatively low pressures compared to centerfire cartridges, the .22 WMR typically produces slightly higher chamber pressure than the .17 HMR. Though this alone isn’t the key reason for incompatibility, it’s a contributing factor that underscores the need for each round to be used with its intended firearm.
Why it’s Not Safe to Shoot .17 HMR in a .22 WMR Firearm
The Hazards of Misfires and Malfunctions
One of the first and most concerning issues is the increased risk of misfires and malfunctions. Because the .17 HMR bullet is smaller in diameter than what your .22 WMR barrel is designed for, the bullet may not seat correctly. The bullet could potentially tumble in the barrel rather than gaining the stability needed for accuracy, and potentially, the shot may not even fire. The rimfire ignition system relies on the firing pin striking the rim of the cartridge. If the round is not properly seated, or the firing pin is unable to strike the rim with enough force, a misfire occurs, which can be an issue on its own.
The potential for malfunctions goes beyond a simple failure to fire. Imagine the .172-inch bullet exiting the casing, engaging the rifling, and then not sealing the bore. The gases could potentially escape around the projectile, leading to inconsistent velocities and erratic bullet flight, which could damage the barrel and cause injury to the shooter or bystanders.
The Risk of Injury and Weapon Failure
Beyond misfires, there’s the very real threat of serious injury and damage to your firearm. When the smaller .17 HMR bullet is fired from a .22 WMR rifle, the following could happen:
- Bullet Fragmentation: The .172-inch bullet may not properly engage the rifling in the .22 WMR barrel. It could potentially fragment, or even disintegrate, mid-flight. This results in a loss of ballistic stability and presents a risk to anything that might be in the bullets path.
- Barrel Damage: If the .17 HMR bullet fails to stabilize as it travels down the barrel, it may cause damage to the rifling. This damage compromises accuracy and can potentially lead to more serious barrel erosion and cracking, which may require replacement of the barrel.
- Blowback: The most severe risk is the potential for blowback. If the bullet doesn’t create a sufficient seal in the barrel, the high-pressure gases from the firing round could escape, potentially injuring the shooter.
These factors highlight why it’s critical to never attempt to use ammunition that isn’t specifically designed for your firearm.
The Crucial Importance of Using Correct Ammunition
Given the inherent risks of mixing ammunition, you might ask, “How do I prevent a mistake?” Here are some crucial tips to avoid the dangerous combination of ammunition:
- Check your ammunition: Before going out into the field, inspect all of your ammunition. You want to make sure you have the correct type of ammunition for the caliber of your firearm.
- Review firearm manufacturer’s recommendations: All firearms come with manufacturer’s recommendations on which types of ammunition to use. If you’re unsure about what to use, look up your manufacturer’s recommendations.
- Identify ammunition: Always label your ammunition. This is especially important if you keep ammunition in different containers or if you have multiple firearms of different calibers.
- Be mindful of headspacing: Always be mindful of the headspacing of your ammunition. If the ammunition is loose in the chamber, it is not safe to shoot.
What Ammunition to Use
When you own a .22 WMR firearm, the only ammunition you should be using is .22 WMR ammunition. This is the only way to ensure the safety and effectiveness of your firearm. This ammunition is readily available at most gun stores and online retailers. You will find a variety of grain weights and bullet types, and the .22 WMR has more energy than the .22 LR, making it suitable for small game hunting.
Conclusion
The answer to the question, *Can you shoot .17 HMR in a .22 Mag?* is a resounding and unequivocal no. The .17 HMR and .22 WMR cartridges, while sharing visual similarities, are fundamentally different. Attempting to interchange them puts you and others in serious danger. The smaller bullet diameter, the potential for pressure issues, and the risk of barrel damage and injury are just some of the critical reasons for extreme caution. Responsible gun ownership includes a deep understanding of the equipment you use and the ammunition it requires. Prioritize your safety, the safety of those around you, and the integrity of your firearm by always using the correct ammunition for your specific firearm.
Remember, safe and informed shooting practices are the cornerstones of a positive and enjoyable experience with firearms. Never take shortcuts when it comes to firearm safety.
