The .22 Advanced Rifle Cartridge (.22 ARC) is a bottlenecked centerfire rifle cartridge designed specifically for the AR-15 platform. It features a standard bullet diameter of .224 inches (5.69 mm). The maximum case length is 1.525 inches (38.74 mm), and the maximum overall cartridge length is 2.260 inches (57.40 mm) to ensure compatibility with standard AR-15 magazines. The case shares its parentage with the 6.5 Grendel, utilizing a rim and base diameter of .441 inches (11.20 mm). Common factory bullet weights range from 62 grains up to heavy 88 grain projectiles. Exact measurements can vary slightly based on manufacturing tolerances, but these specifications adhere strictly to the official SAAMI standards.
.22 ARC Case Dimensions
| Dimension | Specification | Source | Notes |
| Bullet Diameter | .224 in (5.69 mm) | SAAMI | Standard for .22 caliber centerfire rifles. |
| Case Length | 1.525 in (38.74 mm) | SAAMI | Maximum case length. |
| Overall Cartridge Length | 2.260 in (57.40 mm) | SAAMI | Maximum overall length for AR-15 magazines. |
| Rim Diameter | .441 in (11.20 mm) | SAAMI | Requires a 6.5 Grendel Type 2 bolt face. |
| Case Diameter (Base) | .441 in (11.20 mm) | SAAMI | Measured just above the extractor groove. |
| Shoulder Diameter | .430 in (10.92 mm) | Hornady | Features a 30 degree shoulder angle. |
| Neck Diameter | .253 in (6.43 mm) | Hornady | Maximum external diameter at the case mouth. |
| Base Diameter | .441 in (11.20 mm) | SAAMI | Same as the rim diameter. |
| Case Capacity | 34.6 gr H2O | Industry | Measured in grains of water; varies slightly by brass brand. |
| Maximum Pressure | 52,000 psi | SAAMI | Capped for safety in gas operated AR-15 platforms. |
Understanding The .22 ARC Dimensions
- Bullet Diameter: The measurement across the widest point of the bullet. For the .22 ARC, this is specified as .224 inches, identical to the .223 Remington and 5.56 NATO cartridges.
- Case Length: The length of the empty brass cylinder from the base to the case mouth, maxing out at 1.525 inches. This shorter case leaves plenty of room in the magazine for long, aerodynamic bullets.
- Overall Cartridge Length (OAL):The total length of the fully assembled round from the base to the tip of the bullet, strictly capped at 2.260 inches. This dimension guarantees the cartridge will fit inside an AR-15 magazine.
- Rim Diameter: The diameter of the flange at the very bottom of the case (.441 inches). Because it is wider than a standard .223 Remington, you need a specific 6.5 Grendel bolt face to properly grip and extract the rim.
- Case Diameter: The width of the cartridge body at the base. At .441 inches, it is substantially wider than a .223 Remington, allowing it to hold more gunpowder in a shorter package.
- Base Diameter: The width of the brass just above the extractor groove. It must withstand the initial expansion of ignition.
- Case Capacity: Measured in grains of water (gr H2O), this represents the internal volume of the empty case. Averaging 34.6 grains of water, it offers excellent efficiency.
- Maximum Pressure:Standard SAAMI limits set this at 52,000 psi. This relatively moderate pressure limit ensures that standard AR-15 bolt carrier groups do not suffer premature fatigue from the wider .441 inch bolt face.
.22 ARC Cartridge Dimensions In Inches And Millimeters
For engineers, reloaders, and international shooters, below are the primary .22 ARC measurements converted accurately between imperial and metric systems.
| Dimension | Inches (SAAMI Max) | Millimeters (Equivalent) |
| Bullet Diameter | .224 in | 5.69 mm |
| Case Length | 1.525 in | 38.74 mm |
| Overall Length | 2.260 in | 57.40 mm |
| Rim Diameter | .441 in | 11.20 mm |
| Base Diameter | .441 in | 11.20 mm |
| Shoulder Diameter | .430 in | 10.92 mm |
.22 ARC Case Dimensions
The .22 ARC case is essentially a necked down modification of the 6.5 Grendel and 6mm ARC family. The official maximum case length is 1.525 inches, which is slightly longer than the 1.490 inch case of the 6mm ARC, but noticeably shorter than the 1.760 inch case of the .223 Remington.
This shortened case length is intentional. By shrinking the brass down to 1.525 inches, ammunition manufacturers have much more forward space to seat exceptionally long, high ballistic coefficient (BC) bullets entirely outside of the powder column. The case features a steep 30 degree shoulder angle, which promotes efficient powder burn and prevents the brass from stretching excessively during firing.
.22 ARC Bullet Diameter
The standardized maximum bullet diameter for the .22 ARC is .224 inches (5.69 mm). While this is the exact same caliber utilized by the 5.56 NATO and .223 Remington, the .22 ARC chamber is engineered specifically to accommodate modern, heavy for caliber match bullets.
To stabilize these heavy bullets, the SAAMI specified standard twist rate for the .22 ARC is a very fast 1:7 twist. This allows the barrel to spin and stabilize long 75 grain and 88 grain projectiles, something older .22 caliber cartridges like the .22-250 Remington struggle to do with their traditional 1:14 twist rates.
.22 ARC Overall Length
The SAAMI maximum overall cartridge length (OAL) for the .22 ARC is 2.260 inches (57.40 mm). This number is a hard limit established by the physical internal dimensions of standard AR-15 magazines.
Because the .22 ARC case is only 1.525 inches long, a reloader has .735 inches of space left over to seat a projectile before hitting the 2.260 inch magazine limit. This head height is what makes the .22 ARC so versatile, allowing it to chamber massive 88 grain and 90 grain bullets without pushing the projectile so deep into the case that it robs powder capacity.
.22 ARC Chamber And Cartridge Dimensions
The relationship between the .22 ARC cartridge and the firearm’s chamber is critical for accuracy. The .22 ARC cartridge headspaces on its 30 degree shoulder.
This steep shoulder provides a very positive stopping point inside the chamber, keeping the cartridge perfectly aligned with the bore. Because the .22 ARC operates in semi automatic gas guns, the chamber dimensions are cut with just enough tolerance to allow reliable feeding from a magazine while keeping the bullet perfectly concentric to the rifling. The neck diameter of the chamber is optimized to accept the .253 inch maximum external neck diameter of a loaded round.
.22 ARC Dimensions vs Similar Cartridges
To understand the .22 ARC size profile, it is helpful to compare it against other popular rifle cartridges in its class.
| Cartridge | Bullet Diameter | Case Length | Overall Length | Base Diameter | Maximum Pressure |
| .22 ARC | .224 in | 1.525 in | 2.260 in | .441 in | 52,000 psi |
| .223 Remington | .224 in | 1.760 in | 2.260 in | .376 in | 55,000 psi |
| .22-250 Rem | .224 in | 1.912 in | 2.350 in | .473 in | 65,000 psi |
| 6mm ARC | .243 in | 1.490 in | 2.260 in | .441 in | 52,000 psi |
| .22 Creedmoor | .224 in | 1.920 in | 2.825 in | .472 in | 62,000 psi |
.22 ARC vs .223 Remington Dimensions
The .22 ARC and the .223 Remington both shoot .224 inch bullets and fit into AR-15 magazines (2.260 inch OAL), but their cases are completely different.
- Case Length: The .223 Remington case is longer at 1.760 inches compared to the .22 ARC at 1.525 inches.
- Case Width: The .22 ARC is much fatter. Its base measures .441 inches compared to the narrow .376 inch base of the .223 Remington.
- Capacity: Because the .22 ARC is wider, it holds more powder than the .223 Remington despite being shorter.
- Hardware: The .223 Remington uses a standard AR-15 bolt, while the .22 ARC requires a 6.5 Grendel Type 2 bolt face.
You cannot fire a .22 ARC in a .223 Remington chamber, nor can you use .223 Remington magazines reliably with the .22 ARC due to the wider case body.
.22 ARC SAAMI Specifications
The Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) officially standardized the .22 ARC in early 2024.
SAAMI lists the maximum average pressure (MAP) for the .22 ARC at 52,000 psi. This pressure ceiling was chosen specifically to protect standard AR-15 bolt carrier groups. Because the .441 inch rim requires a wider bolt face, less steel is left on the bolt lugs compared to a standard 5.56 NATO bolt. Keeping the pressure at 52,000 psi ensures the rifle cycles safely without shearing bolt lugs over time.
.22 ARC Bullet Weight And Dimensions
The .22 ARC was built from the ground up to utilize modern, heavy bullets. Common factory loads include:
- 62 grain ELD-VT:Sits perfectly in the 1.525 inch case and delivers extremely flat trajectories for varmint hunting.
- 75 grain ELD Match: A mid weight target bullet that balances velocity and wind resistance.
- 88 grain ELD Match:A very long, heavy bullet that maximizes the 2.260 inch overall length restriction to provide incredible long range performance.
Lighter bullets can be used, but the cartridge dimensions and 1:7 twist rate are optimized for projectiles weighing 62 grains or more.
Why .22 ARC Dimensions Matter
Understanding the specific .22 ARC measurements is essential for several practical reasons:
- AR-15 Upgrades:Knowing the .441 inch rim diameter reminds builders that they need a specific 6.5 Grendel bolt face and 6.5 Grendel style magazines to feed the .22 ARC properly.
- Bullet Selection: Because the case is only 1.525 inches long, reloaders have the freedom to seat massive 90 grain target bullets without exceeding the AR-15 magazine limits.
- Safe Reloading: Adhering to the 52,000 psi limit is critical to prevent damaging gas operated rifles.
Manufacturer Specifications vs Independent Measurements
If you measure factory .22 ARC ammunition from companies like Hornady, the numbers will rarely match the SAAMI maximum specifications exactly.
SAAMI publishes the maximum allowable dimensions to ensure safety across all firearms. Ammunition manufacturers purposefully produce their cases slightly smaller than these maximums. For example, the maximum case length is 1.525 inches, but Hornady lists the ideal trim to length for reloaders at 1.510 inches. This built in tolerance guarantees that the ammunition will chamber reliably even if the rifle is dirty from high volume varmint hunting.
Common Questions
What are the dimensions of the .22 ARC?
The key maximum dimensions are a bullet diameter of .224 inches, a case length of 1.525 inches, and an overall cartridge length of 2.260 inches.
What is the .22 ARC case length?
The maximum SAAMI case length is 1.525 inches (38.74 mm).
What is the .22 ARC overall length?
The maximum overall length (OAL) is 2.260 inches (57.40 mm), designed to fit flush inside standard AR-15 magazines.
What is the .22 ARC bullet diameter?
The standard bullet diameter is .224 inches.
What is the .22 ARC rim diameter?
The rim diameter measures .441 inches, which requires a 6.5 Grendel Type 2 bolt face.
What is the .22 ARC case capacity?
The .22 ARC holds approximately 34.6 grains of water, giving it a larger capacity than a standard .223 Remington.
What is the maximum pressure for the .22 ARC?
The SAAMI maximum average pressure is strictly capped at 52,000 psi for safe operation in AR-15 rifles.
What parent case is the .22 ARC based on?
The .22 ARC shares its case head and basic body design with the 6.5 Grendel and 6mm ARC.
Does the .22 ARC use the same bolt as a .223?
No. The .223 uses a .378 inch bolt face, while the .22 ARC requires a .441 inch bolt face.