22 LR Case Dimensions

The .22 Long Rifle (.22 LR) features a maximum case length of 0.613 inches (15.57 mm), a rim diameter of 0.278 inches (7.06 mm), a rim thickness of 0.043 inches (1.09 mm), a base and body diameter of 0.226 inches (5.74 mm), a case mouth diameter of 0.226 inches (5.74 mm), and a maximum overall cartridge length of 1.000 inches (25.40 mm). Published numerical specifications represent nominal manufacturing targets, maximum allowable boundaries, or MIN/MAX tolerance windows depending on whether SAAMI or C.I.P. standards are cited. SAAMI regulates voluntary dimensions in North America, whereas C.I.P. enforces mandatory proof standards across Europe. Internal case capacity and physical tolerances show subtle variations among major manufacturers such as CCI, Eley, Lapua, Federal, Winchester, and Remington. Understanding these standardized measurements ensures proper rim headspacing, reliable firearm extraction, flawless magazine cycling, and safe operating pressures.

22 LR Case Dimensions

Case Dimension	Inches	Millimeters	Specification Type	Source	Notes
Case Length	0.613 in	15.57 mm	Maximum	SAAMI Standard	Tolerance: -0.020 in (-0.51 mm)
Rim Diameter	0.278 in	7.06 mm	Maximum	SAAMI Standard	Tolerance: -0.010 in (-0.25 mm)
Rim Thickness	0.043 in	1.09 mm	Maximum	SAAMI Standard	Tolerance: -0.007 in (-0.18 mm)
Base Diameter	0.226 in	5.74 mm	Maximum	SAAMI Standard	Tolerance: -0.004 in (-0.10 mm)
Body Diameter	0.226 in	5.74 mm	Maximum	SAAMI Standard	Straight cylindrical body without shoulder
Mouth Diameter	0.226 in	5.74 mm	Maximum	SAAMI Standard	Outer diameter matches body diameter
Heel Diameter	0.208 in	5.28 mm	Nominal Reference	Reference Standard	Projectile heel fits inside case mouth
Shoulder Angle	N/A	N/A	Straight Case	SAAMI Standard	Unbottlenecked rimfire design
Overall Cartridge Length	1.000 in	25.40 mm	Maximum	SAAMI Standard	Nominal testing COAL is 0.975 to 0.995 in
Case Capacity	6.0 gr H2O	0.39 cm³	Nominal Average	Lapua / Eley	Varies by brand (5.8 to 6.2 gr H2O)
Maximum Pressure	24,000 PSI	1,700 bar	Maximum Allowable	SAAMI MAP	C.I.P. Pmax is set at 1,700 bar (24,656 PSI)

Understanding The 22 LR Case Dimensions

Evaluating the .22 LR technical profile requires understanding how each structural measurement operates within a firearm chamber:

• Case Length: The total distance from the exterior face of the rim to the case mouth. Proper case length ensures the mouth seats cleanly in the chamber step without obstructing bullet release.
• Rim Diameter: The outer boundary of the hollow rim fold. The rim stops forward travel in the chamber and provides the gripping surface for extractors.
• Rim Thickness: The vertical depth of the rim wall containing the spinning-applied priming compound. This dimension controls headspacing and firing pin crush efficiency.
• Base Diameter: The exterior body width located forward of the rim junction. It governs rear chamber clearance and expansion.
• Body Diameter: The outer measurement along the straight case wall. Because the .22 LR is a straight-walled case, the body diameter remains uniform at 0.226 inches from base to mouth.
• Mouth Diameter: The exterior case diameter at the front edge. It matches the body diameter and flush-fits the driving band of the specialized heeled projectile.
• Heel Diameter: The reduced rear step of the projectile shank that fits internally into the brass mouth, allowing the outer bullet driving band to remain flush with the 0.226 inch case exterior.
• Overall Cartridge Length: The total length from the base of the rim to the tip of the projectile. It ensures smooth feeding through rotary, tube, and box magazines.
• Case Capacity: The volume of water held by a fired, unprimed case filled flush to the mouth. Small volume shifts alter chamber pressure significantly due to compact powder charges.

22 LR Case Dimensions In Inches And Millimeters

The following reference table converts primary SAAMI and C.I.P. .22 LR dimensions into imperial and metric units.

Dimension Description	Inches (Imperial)	Millimeters (Metric)	Type / Definition
Maximum Case Length	0.613 in	15.57 mm	Upper limit for raw brass length
Minimum Case Length	0.593 in	15.06 mm	Lower SAAMI manufacturing limit
Target Manufacturing Length	0.605 in	15.37 mm	Standard factory casing baseline
Maximum Rim Diameter	0.278 in	7.06 mm	Rim width for extraction and seating
Minimum Rim Diameter	0.268 in	6.81 mm	Lower limit for rim forming
Maximum Base Diameter	0.226 in	5.74 mm	Width forward of rim fold
Maximum Body Diameter	0.226 in	5.74 mm	Straight cylindrical outer wall
Maximum Mouth Diameter	0.226 in	5.74 mm	External mouth matching body width
Bullet Driving Band Diameter	0.2255 in	5.73 mm	Maximum exterior projectile diameter
Maximum Overall Length (COAL)	1.000 in	25.40 mm	Maximum clearance limit for magazines

22 LR Case Length

The published maximum case length for the .22 LR is 0.613 inches (15.57 mm) under SAAMI standards, while C.I.P. documentation lists maximum case length as 15.57 mm. The minimum manufacturing limit under SAAMI is 0.593 inches (15.06 mm).

Because .22 LR cartridges are rimfire and non-reloadable, handloading trim specs do not apply. However, case length consistency remains critical for firearm operation. In blowback semi-automatic rifles and pistols, the thin brass expands to seal the chamber walls upon ignition. If a case exceeds 0.613 inches, the mouth can wedge into the forward chamber driving step, impeding proper bolt lockup, causing extraction failures, or generating irregular pressure variations during bullet departure.

22 LR Base And Rim Dimensions

The .22 LR utilizes a rimmed design with a maximum rim diameter of 0.278 inches (7.06 mm), a maximum base diameter of 0.226 inches (5.74 mm), and a maximum rim thickness of 0.043 inches (1.09 mm).

Unlike centerfire rounds that headspace on a shoulder or datum line, the .22 LR headspaces entirely on the front face of its hollow rim. The rim rests against the barrel counterbore face, establishing proper depth inside the chamber. When the firing pin strikes the outer edge of the rim, it crushes the brass rim wall against the breech face, detonating the internal priming compound. Consistent rim thickness across production lots is essential for uniform primer crush and tight shot-to-shot velocity spreads.

22 LR Body And Neck Dimensions

Unlike bottlenecked rifle cartridges, the .22 LR features a straight-walled case profile without a traditional neck or shoulder:

• Body Diameter: 0.226 inches (5.74 mm) maximum along the entire case body.
• Shoulder Angle: Zero degrees (straight cylinder design).
• Mouth Diameter: 0.226 inches (5.74 mm) maximum.
• Projected Heel Joint: Accepts a stepped bullet shank measuring approximately 0.208 inches (5.28 mm) internally.

This straight cylindrical body requires a unique heeled projectile design. The rear shank of the bullet is stepped down to roughly 0.208 inches to fit inside the case mouth, while the forward driving bands measure 0.223 to 0.2255 inches. This construction allows the outer diameter of the bullet driving band to flush-match the 0.226 inch exterior wall of the brass case.

22 LR Case Capacity

The internal water capacity of a .22 LR case averages approximately 6.0 grains H2O (0.39 cm³) when measured flush with the mouth on a fired case. Volume typically spans between 5.8 grains H2O and 6.2 grains H2O depending on brass wall thickness.

Capacity variations exist across major manufacturers:

• Match Brass (Eley / Lapua): Utilizes highly uniform drawing processes yielding internal volume near 5.9 to 6.0 grains H2O with tight weight consistency.
• Commercial Bulk Brass (CCI / Federal / Winchester): Typically spans 6.0 to 6.2 grains H2O.

Because .22 LR propellants consist of tiny charges (typically 1.0 to 2.5 grains of fast-burning smokeless powder), a shift of just 0.1 grains of powder or a minor drop in internal case capacity causes a measurable change in velocity and chamber pressure.

22 LR Bullet Diameter

The standardized maximum bullet driving band diameter for the .22 LR is 0.2255 inches (5.73 mm) under SAAMI guidelines, with commercial bullet diameters typically measuring between 0.223 inches and 0.225 inches.

Understanding the relationship between projectile dimensions and barrel dimensions is vital:

• Bullet Driving Band Diameter: 0.223 in to 0.2255 in (5.66 mm to 5.73 mm).
• Bullet Heel Diameter: ~0.208 in (5.28 mm).
• Bore Diameter (Land to Land): 0.217 in (5.51 mm).
• Groove Diameter (Groove to Groove): 0.222 in (5.64 mm).

When fired, the soft lead alloy bullet expands slightly under pressure (obturation), causing the driving bands to engage the 0.217 inch rifling lands and seal completely against the 0.222 inch groove diameter.

22 LR Overall Cartridge Length

SAAMI specifies a maximum overall cartridge length (COAL) of 1.000 inch (25.40 mm) for the .22 LR. Standard production factory rounds generally measure between 0.970 inches and 0.995 inches depending on the nose profile.

This 1.000 inch length boundary is a critical constraint for repeating firearms. Rotary magazines (such as Ruger 10/22 magazines), tubular feed ramps, and box magazines are manufactured around this dimension. Projectiles with elongated round-nose, hollow-point, or flat-meplat geometries must maintain an overall length below 1.000 inch to prevent tip dragging and feeding failures against the chamber ramp.

22 LR Dimensions vs Similar Cartridges

Comparing the .22 LR against structurally related rimfire cartridges highlights key dimensional differences.

Cartridge	Bullet Diameter	Case Length	Overall Length	Rim / Base Diameter	Case Capacity	Source
.22 LR	0.2255 in (5.73 mm)	0.613 in (15.57 mm)	1.000 in (25.40 mm)	0.278 in / 0.226 in	~6.0 gr H2O	SAAMI
.22 Short	0.2255 in (5.73 mm)	0.423 in (10.74 mm)	0.695 in (17.65 mm)	0.278 in / 0.226 in	~4.0 gr H2O	SAAMI
.22 Long	0.2255 in (5.73 mm)	0.613 in (15.57 mm)	0.895 in (22.73 mm)	0.278 in / 0.226 in	~6.0 gr H2O	SAAMI
.22 WMR (Magnum)	0.2240 in (5.69 mm)	1.055 in (26.80 mm)	1.350 in (34.29 mm)	0.294 in / 0.242 in	~11.0 gr H2O	SAAMI
.17 HMR	0.1720 in (4.37 mm)	1.055 in (26.80 mm)	1.349 in (34.26 mm)	0.294 in / 0.242 in	~9.1 gr H2O	SAAMI
.17 HM2 (Mach 2)	0.1720 in (4.37 mm)	0.613 in (15.57 mm)	1.000 in (25.40 mm)	0.278 in / 0.226 in	~5.2 gr H2O	SAAMI
.22 Extra Long	0.2255 in (5.73 mm)	0.750 in (19.05 mm)	1.180 in (29.97 mm)	0.278 in / 0.226 in	~8.0 gr H2O	Historical

Dimensional similarities do not indicate interchangeable ammunition. Each cartridge requires its specific dedicated chamber.

22 LR vs 22 WMR Case Dimensions

Although both cartridges fire .22 caliber bullets, the .22 LR and .22 WMR (.22 Winchester Magnum Rimfire) differ significantly in case construction:

• Case Diameter: The .22 WMR features a larger base diameter of 0.242 inches (6.15 mm) and a rim diameter of 0.294 inches (7.47 mm), compared to the .22 LR base diameter of 0.226 inches and rim diameter of 0.278 inches.
• Case Length: The .22 WMR case length is 1.055 inches (26.80 mm), compared to 0.613 inches (15.57 mm) for the .22 LR.
• Bullet Mounting: The .22 LR uses an outside-lubricated heeled bullet flush with the case body. The .22 WMR uses a true jacketed bullet seated internally inside a thicker brass mouth, similar to centerfire rifle rounds.
• Chamber Interchangeability: A .22 LR round must never be fired in a .22 WMR chamber. The wider .22 WMR chamber will cause the thinner .22 LR brass to burst upon ignition, releasing dangerous high-pressure gas.

22 LR vs 17 HMR Case Dimensions

Comparing the .22 LR to the .17 HMR (.17 Hornady Magnum Rimfire) demonstrates the contrast between classic straight-walled rimfire design and modern bottlenecked geometry:

• Parent Design: The .17 HMR is constructed by necking down the .22 WMR case, making it wider and longer than the .22 LR foundation.
• Base and Rim Width: The .17 HMR uses a 0.294 inch rim and 0.242 inch base diameter, exceeding the .22 LR’s 0.278 inch rim and 0.226 inch base.
• Shoulder and Neck: The .17 HMR incorporates a sharp 25 degree shoulder and a 0.193 inch neck holding a 0.172 inch projectile. The .22 LR has no shoulder and features a straight 0.226 inch body.
• Case Length: The .17 HMR case length is 1.055 inches (26.80 mm) versus 0.613 inches (15.57 mm) for the .22 LR.

22 LR vs 22 Short Case Dimensions

The .22 Short is the historic predecessor to the .22 LR, sharing key base and rim dimensions:

• Rim and Base Diameter: Both cartridges use identical rim diameters (0.278 in) and base diameters (0.226 in).
• Case Length: The .22 Short features a substantially shorter case length of 0.423 inches (10.74 mm) compared to 0.613 inches (15.57 mm) for the .22 LR.
• Overall Length: The .22 Short maximum COAL is 0.695 inches (17.65 mm), while the .22 LR maximum COAL is 1.000 inch (25.40 mm).
• Bullet Weight: The .22 Short typically loads lighter 27 to 29 grain projectiles, whereas the .22 LR standardizes on 36 to 40 grain projectiles.

22 LR Chamber And Case Dimensions

Because the .22 LR is utilized across diverse disciplines ranging from general plinking to Olympic target competition, chamber dimensions vary significantly between firearm designs.

SAAMI defines several distinct chamber profiles:

• Sporting Chamber: Cut with generous tolerances (body width ~0.227 in to 0.228 in, length ~0.675 in) to ensure flawless feeding and extraction of varied bulk ammunition in semi-automatic platforms.
• Bentz Chamber: Designed specifically for semi-automatic target rifles, narrowing body dimensions (~0.2255 in) to align cartridges tightly while maintaining reliable feeding.
• Match Chamber (Eley / Anschütz / Win 52): Machined to extremely tight dimensions where the bullet driving band engages the rifling lands directly upon bolt closure. This tight spatial alignment eliminates bullet jump, maximizing target precision.
• Headspace Clearance: Established by counterbore rim depth. Standard headspace clearance between bolt face and barrel face is kept between 0.043 inches and 0.050 inches.

22 LR Case Manufacturing And Specifications

The production of .22 LR brass differs fundamentally from centerfire ammunition manufacturing due to its rimfire primer structure.

Key manufacturing concepts include:

• Deep Drawing: Solid brass discs are drawn into thin, straight-walled cylindrical cups measuring 0.613 inches long with a uniform 0.226 inch diameter.
• Rim Folding: The closed base of the cup is stamped to form a hollow exterior rim cavity measuring 0.278 inches across and 0.043 inches thick.
• Liquid Priming: Wet priming compound is dropped into the case and rapidly spun, using centrifugal force to pack the chemical compound into the hollow rim fold.
• Heeled Seating: The bullet heel (~0.208 in) is inserted into the case mouth, and a subtle roll crimp is applied into the bullet heel groove, securing the projectile without expanding the 0.226 inch outer wall profile.

22 LR Manufacturer Specifications vs Actual Measurements

Real-world measurements often reveal minor variations when comparing standard drawings, match ammunition, and fired brass:

• SAAMI Specifications: Define absolute upper limits for cartridges and lower limits for chambers to ensure universal safety across North America.
• C.I.P. Specifications: Regulate mandatory dimensions across European proof houses. C.I.P. sets maximum case length at 15.57 mm and maximum allowable pressure at 1,700 bar.
• Factory Ammunition Measurements: Unfired rounds from CCI, Eley, or Lapua measure slightly below SAAMI maximums (typically 0.224 to 0.225 in body diameter) to guarantee seamless chambering.
• Fired Brass Dimensions: In blowback actions, fired brass expands to match the exact dimensions of the rifle chamber, causing fired body measurements to increase by 0.001 to 0.003 inches over unfired factory specifications.

Official SAAMI and C.I.P. technical drawings remain the primary standards for dimensional verification.

Common Questions

What are the 22 LR case dimensions?

Key maximum SAAMI specifications include a case length of 0.613 in (15.57 mm), rim diameter of 0.278 in (7.06 mm), rim thickness of 0.043 in (1.09 mm), base/body diameter of 0.226 in (5.74 mm), mouth diameter of 0.226 in (5.74 mm), and maximum COAL of 1.000 in (25.40 mm).

What is the 22 LR case length?

The maximum SAAMI case length is 0.613 inches (15.57 mm), with a minimum manufacturing threshold of 0.593 inches (15.06 mm).

What is the 22 LR rim diameter?

The maximum rim diameter is 0.278 inches (7.06 mm), with a manufacturing tolerance of -0.010 inches (-0.25 mm).

What is the 22 LR base diameter?

The maximum base diameter measured immediately forward of the rim is 0.226 inches (5.74 mm).

What is the 22 LR body diameter?

The maximum body diameter along the straight cylindrical wall is 0.226 inches (5.74 mm).

What is the 22 LR mouth diameter?

The maximum mouth diameter is 0.226 inches (5.74 mm), flush-matching the outer driving bands of the heeled projectile.

What is the 22 LR case capacity?

Nominal water capacity averages 6.0 grains H2O (0.39 cm³), spanning from 5.8 to 6.2 grains H2O depending on brass wall thickness.

What is the 22 LR overall cartridge length?

Maximum overall cartridge length (COAL) is 1.000 inch (25.40 mm) to ensure compatibility with standard magazines and action feed ramps.

How does 22 LR compare with 22 WMR case dimensions?

The .22 LR is a smaller, heeled-bullet rimfire cartridge (0.226 in base, 0.613 in case length) compared to the larger .22 WMR (0.242 in base, 1.055 in case length) which uses an internally seated bullet inside a wider case mouth.

How does 22 LR compare with 17 HMR case dimensions?

The .22 LR is a straight-walled cartridge (0.226 in base, 0.613 in length) holding a .2255 in bullet, whereas the .17 HMR is a longer, bottlenecked cartridge (0.242 in base, 1.055 in length) holding a .172 in bullet with a 25 degree shoulder.

How does 22 LR compare with 22 Short case dimensions?

The .22 LR and .22 Short share identical rim (0.278 in) and base (0.226 in) diameters, but the .22 LR features a longer case length (0.613 in vs 0.423 in) and higher overall length (1.000 in vs 0.695 in).

What is the 22 LR maximum pressure?

The SAAMI Maximum Average Pressure (MAP) is 24,000 PSI. C.I.P. regulates maximum pressure (Pmax) at 1,700 bar (24,656 PSI).