Rimfire FAQ: what, why, when, how and where

A cartridge whose priming mix sits inside the hollow rim of the case; the firing pin crushes the rim to fire it.^{[NIJ firearms examiner training][Shooting Sports USA]}

Long Rifle, the cartridge J. Stevens Arms introduced in 1887.^[Wikipedia]

SAAMI's Maximum Average Pressure for .22 LR is 24,000 psi.^{[ANSI/SAAMI Z299.1-2026 (rimfire)]}

A Winchester rimfire launched in 2024 that uses the .22 LR case with a smaller, non-heeled .21-caliber bullet, at the same 24,000 psi MAP.^{[Winchester][SAAMI]}

A bullet the same diameter as the case, with a narrower heel that fits inside the case mouth, as on .22 LR.^[Wikipedia]

Ammo slower than the speed of sound; CCI uses 1,125 fps as the dividing line.^[CCI]

Standard velocity loads like CCI SV run about 1,070 fps; high velocity loads like Mini-Mag about 1,260 fps.^{[CCI (Standard Velocity 1,070 fps)][CCI 2026 catalog]}

Very low-powered .22 loads; CCI's CB Long fires a 29 gr bullet at 710 fps.^{[CCI CB Long (29 gr, 710 fps)]}

Hornady's 2002 rimfire magnum, a .22 WMR case necked to .17 caliber; the original load was 17 gr at 2,550 fps.^{[Chuck Hawks]}

Winchester's .22 Magnum from 1959; CCI's Maxi-Mag pushes 40 gr at 1,875 fps.^{[Wikipedia][CCI Maxi-Mag .22 WMR (40 gr, 1,875 fps)]}

A delayed ignition after the firing pin falls; SAAMI groups it with misfires as a failure to fire.^{[SAAMI glossary]}

ANSI/SAAMI Z299.1, updated in 2026 and free to read on SAAMI's site.^{[SAAMI][SAAMI]}

The priming is part of the case and the fired rim is crushed; re-priming needs specialized tooling, so it's impractical.^{[American Rifleman]}

The rim must be thin enough to crush, which makes it the weak point; .22 LR is capped at 24,000 psi.^{[American Rifleman][ANSI/SAAMI Z299.1-2026 (rimfire)]}

Ignition depends on priming mix being spread evenly around the rim, and voids cause misfires.^{[NIJ firearms examiner training][American Rifleman]}

Low recoil, low cost and huge rifle choice; American Rifleman calls it the most popular cartridge in the world.^{[American Rifleman]}

Very quiet loads like CCI Quiet-22 (710 fps) may lack the energy to cycle a blowback action.^{[CCI 2026 catalog]}

Demand surges outran production, and rimfire capacity is slow and costly to expand.^{[American Rifleman][Guns.com][American Rifleman]}

Rimfire consistency varies by lot, which is why makers like Lapua run lot-testing centers.^{[Lapua Rimfire Performance Center][Lapua rimfire test shooting]}

Flobert's parlor cartridge dates to 1845.^{[Smith & Wesson][NIJ firearms examiner training]}

1857, with the Smith & Wesson Model 1 revolver.^{[Smith & Wesson][Wikipedia]}

1887, from J. Stevens Arms & Tool Co.^{[Wikipedia][American Rifleman]}

Wikipedia's cartridge table dates it to 2012; one secondary source says 2005, which we believe is wrong.^{[Wikipedia][Grokipedia]}

Follow your manual; see our cleaning guide for intervals from barrel makers.^{[Ruger 10/22 instruction manual][CZ 457 instruction manual (03/2024)]}

For deer and other big game, which many states reserve for centerfire; Indiana, for example, requires centerfire cartridges for deer.^{[Indiana DNR deer hunting equipment]}

Introduced 1969 or 1970 depending on the source; rifles were dropped after 1974.^{[American Hunter][Chuck Hawks]}

The firing pin crushes the rim against the chamber edge, igniting the priming mix, which lights the powder.^{[Shooting Sports USA][American Rifleman]}

SAAMI says to keep the muzzle safe and wait several seconds; other guidance suggests longer, and 30 seconds is a cautious habit.^{[SAAMI FAQs][Hunter-ed.com]}

In original packaging, cool and dry, away from heat and solvents, and away from children.^[SAAMI]

Far enough that a safe backstop is essential; see our guide.^{[Hunter-ed.com]}

NRL22 publishes a monthly course of fire shot at local clubs; start there.^{[NRL22 FAQ]}

A wet pellet is dropped in and spun outward into the rim, then dried.^{[NIJ firearms examiner training][American Rifleman]}

Hyper-velocity loads like CCI Stinger run 1,640 fps with a 32 gr bullet.^{[CCI Stinger (32 gr, 1,640 fps)]}

Ranges and clubs are easiest; on other land, follow local rules and use a safe backstop.^{[Hunter-ed.com]}

SAAMI publishes rimfire pressure, velocity and dimension standards for free.^[SAAMI]

ISSF 50 m rifle events and biathlon both use .22 LR rifles.^{[ISSF general technical rules (2023)][IBU event and competition rules annexes (2024)]}

ARA and RBA clubs shoot 25-bull cards at 50 yd from rests.^{[ARA rule book (Jan 1, 2026)][River Bend Gun Club]}

Ruger says moderate dry firing of the 10/22 is fine for function checks but use snap caps for extensive practice; CZ discourages excessive dry firing of the 457.^{[Ruger 10/22 instruction manual][CZ 457 instruction manual (03/2024)]}

Usually it will chamber and fire; semi-autos may not cycle it. Check your manual.^[Wikipedia]

No. It physically fits, but American Rifleman says you need a .21 Sharp barrel; and .22 LR won't fit a .21 Sharp chamber.^{[American Rifleman]}