Rimfire Ammo

Rimfire vs. Centerfire

Rimfire cartridges have their primer compound embedded in the rim of the case, which is struck by the firing pin to ignite the powder charge. This design is simple and inexpensive to manufacture but means rimfire cases cannot be reloaded—once fired, they’re spent. Rimfire calibers are generally lower-pressure and lower-powered than centerfire, making them ideal for small game, introductory shooting, and practice. The .22 LR is by far the most popular rimfire caliber; .22 WMR, .17 HMR, and .17 WSM offer meaningfully higher velocity for extended small game range.

Choosing a Rimfire Caliber

The .22 LR is the right choice for most shooters—it’s the most affordable, most widely available, and chambers in the widest selection of rifles and pistols. The .22 WMR (Magnum) offers more power and range for small game at a higher per-round cost. The .17 HMR and .17 WSM are purpose-built varmint cartridges, firing a very light, fast bullet with a flat trajectory out to 200 yards. If your primary use is practice and general plinking, .22 LR wins on cost and platform selection. If you’re hunting prairie dogs or squirrels at distance, .17 HMR or .17 WSM is worth the premium.

Suppressor Use

Rimfire calibers—particularly .22 LR—are extremely popular for suppressor use. Standard velocity and subsonic .22 LR loads are already below the speed of sound from most rifle barrels and produce minimal noise when suppressed, making the combination one of the most accessible suppressed shooting setups available. The .22 WMR and .17 HMR are supersonic by design and cannot be loaded subsonic, so they produce a supersonic crack even when suppressed—suppression reduces muzzle blast but not the ballistic crack.

Reliability and Semi-Auto Cycling

Rimfire ammunition is inherently less reliable than centerfire due to the rim-priming design and lower pressures involved. Most quality rimfire loads function reliably in well-maintained firearms, but occasional misfires are more common than with centerfire ammunition. For semi-automatic rimfire rifles and pistols, standard velocity or high velocity loads from CCI, Federal, and Winchester cycle reliably in most platforms. Bulk budget loads are more prone to cycling failures in picky semi-autos; CCI Mini-Mag is the most widely recommended load for reliable semi-auto cycling.

Match Rimfire

Rimfire competition is a significant and growing discipline, with precision rimfire matches at distances from 50 yards to 300 yards growing rapidly. Match-grade .22 LR from Eley, Lapua, RWS, and CCI Custom Grade is purpose-built for these applications, offering velocity consistency and bullet quality that bulk ammunition cannot approach. Match rimfire performance is highly rifle-dependent—a premium lot that shoots superbly in one barrel may perform only modestly in another. Serious competitors test multiple lots and manufacturers to identify the best combination for their specific rifle.

Frequently Asked Questions: Rimfire Ammunition

What is the difference between .22 LR and .22 WMR?
.22 LR (Long Rifle) is the world’s most common rimfire cartridge — low cost, widely available, minimal recoil, suitable for everything from target shooting to small game. .22 WMR (Winchester Magnum Rimfire, also called .22 Mag) is a larger, more powerful cartridge producing roughly twice the muzzle energy of .22 LR — more effective for small game and varmints at longer ranges but more expensive and not interchangeable with .22 LR firearms. The two use different-sized cases and cannot be interchanged.

Why is .22 LR ammo sometimes unreliable in semi-autos?
Rimfire ammunition relies on an impact-sensitive priming compound distributed around the case rim rather than a centralized primer. This design is more sensitive to priming consistency than centerfire ammunition. Budget bulk .22 LR has higher failure rates than match-grade or quality production ammo. For semi-automatic .22 rifles and pistols, CCI Mini-Mag and Federal Auto Match are the standard reliability recommendations — both cycle semi-autos more consistently than bulk surplus or economy bulk packs.

What is the best .22 LR ammo for accuracy?
For target shooting and competition, Eley Tenex, Lapua Center-X, and CCI Standard Velocity are the benchmarks. For hunting small game, CCI Mini-Mag and CCI Velocitor offer reliable expansion at higher velocity. For suppressed use, CCI Quiet and CCI Standard Velocity (which is naturally subsonic from most barrels) are the standard recommendations.

What rimfire calibers can I use with a suppressor?
.22 LR is the most popular suppressed rimfire — standard velocity and subsonic loads are hearing-safe through most quality .22 suppressors. .22 WMR is supersonic and produces a ballistic crack a suppressor cannot eliminate, though it still reduces muzzle blast significantly. .17 HMR is supersonic and suppresses less effectively than subsonic .22 LR.

See Also: .22 LR Ammo • .22 WMR Ammo • .17 HMR Ammo • .22 Rifles • Suppressors