The .223 Remington is a bottlenecked centerfire rifle cartridge featuring a standard maximum bullet diameter of .224 inches (5.69 mm). The maximum case length is 1.760 inches (44.70 mm), and the maximum overall cartridge length is restricted to 2.260 inches (57.40 mm) to ensure compatibility with standard magazines. The case utilizes a rim diameter of .378 inches (9.60 mm) and a base diameter of .376 inches (9.55 mm). Ammunition for this caliber is most commonly found in 55 grain, 62 grain, 69 grain, and 77 grain bullet weights. Exact dimensions and operating pressures can vary slightly depending on manufacturing tolerances and whether you reference American SAAMI specifications or European C.I.P. standards.
.223 Remington Dimensions
| Dimension | Specification | Source | Notes |
| Bullet Diameter | .224 in (5.69 mm) | SAAMI / C.I.P. | Standard for .22 caliber centerfire rifles. |
| Case Length | 1.760 in (44.70 mm) | SAAMI | Maximum case length; trim to length is typically 1.750 in. |
| Overall Cartridge Length | 2.260 in (57.40 mm) | SAAMI | Maximum overall length for standard AR-15 style magazines. |
| Rim Diameter | .378 in (9.60 mm) | SAAMI | Maximum rim diameter. |
| Case Diameter (Base) | .376 in (9.55 mm) | SAAMI | Measured just above the extractor groove. |
| Shoulder Diameter | .354 in (8.99 mm) | SAAMI | Features a 23 degree shoulder angle. |
| Neck Diameter | .253 in (6.43 mm) | SAAMI | Maximum external diameter at the case mouth. |
| Base Diameter | .376 in (9.55 mm) | SAAMI | Measured just above the extractor groove. |
| Case Capacity | 28.8 to 31.4 gr H2O | Industry Standard | Varies slightly based on brass manufacturer and wall thickness. |
| Maximum Pressure | 55,000 psi | SAAMI | C.I.P. maximum is 430 MPa (approximately 62,366 psi). |
Understanding The .223 Remington Dimensions
- Bullet Diameter: The measurement across the widest point of the bullet. For the .223 Remington, this is specified as .224 inches. This dimension ensures the projectile seals properly within the barrel rifling to trap expanding gases.
- Case Length: The length of the empty brass cylinder from the base to the case mouth, maxing out at 1.760 inches. If the case is too long, it can pinch the bullet in the chamber throat and cause dangerous pressure spikes.
- 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. OAL directly influences whether a cartridge will fit into a standard magazine and feed properly.
- Rim Diameter: The diameter of the flange at the very bottom of the case measuring .378 inches. The firearm extractor hooks onto this rim to pull the spent casing out of the chamber.
- Base Diameter: The width of the brass just above the extractor groove measuring .376 inches. It must withstand the initial expansion of ignition.
- Shoulder Diameter: The width of the case where it begins to angle inward toward the neck measuring .354 inches. The .223 Remington uses this 23 degree shoulder to headspace inside the chamber.
- Case Capacity: Measured in grains of water (gr H2O), this represents the internal volume of the empty case. It dictates how much gunpowder the case can safely hold.
- Maximum Pressure: The peak internal pressure generated when the cartridge is fired. Standard SAAMI limits set this at 55,000 psi for the .223 Remington.
.223 Remington Cartridge Dimensions In Inches And Millimeters
For engineers, reloaders, and international shooters, below are the primary .223 Remington measurements converted accurately between imperial and metric systems.
| Dimension | Inches (SAAMI Max) | Millimeters (Equivalent) |
| Bullet Diameter | .224 in | 5.69 mm |
| Case Length | 1.760 in | 44.70 mm |
| Overall Length | 2.260 in | 57.40 mm |
| Rim Diameter | .378 in | 9.60 mm |
| Base Diameter | .376 in | 9.55 mm |
| Shoulder Diameter | .354 in | 8.99 mm |
| Neck Diameter | .253 in | 6.43 mm |
.223 Remington Case Dimensions
The .223 Remington is defined by a rimless, bottlenecked case. The official maximum case length is 1.760 inches (44.70 mm), with a nominal trim to length for reloaders sitting at 1.750 inches. The base diameter measures .376 inches, and the rim diameter is slightly larger at .378 inches.
The brass case walls are subjected to intense expansion stresses upon firing. Because of differences in manufacturing, internal case capacity can range anywhere from 28.8 to 31.4 grains of water. Thicker brass, such as military surplus or certain match grade brands, has less internal volume. This means reloaders must adjust their powder charges depending on the exact dimensions of the brass brand they are using.
.223 Remington Bullet Diameter
The standardized maximum bullet diameter for the .223 Remington is .224 inches (5.70 mm). It is vital not to confuse the bullet diameter with the barrel internal dimensions.
The standard .223 Remington barrel features a groove diameter of .224 inches and a bore or land diameter of .219 inches. Firing a .224 inch bullet down a .219 inch bore diameter forces the bullet to engrave into the rifling, creating the spin necessary to stabilize the projectile in flight.
.223 Remington Overall Length
The SAAMI maximum overall cartridge length (OAL) for the .223 Remington is 2.260 inches (57.40 mm). This number is a hard limit designed to guarantee that the cartridge will fit inside standard AR-15 and bolt action magazines.
Typical factory cartridge length varies based on the bullet profile. A classic 55 grain Full Metal Jacket round typically measures right at the 2.260 inch maximum. However, lighter 40 grain varmint bullets or bullets with blunt hollow point profiles are seated deeper, often resulting in an OAL of 2.200 to 2.230 inches.
.223 Remington Chamber And Cartridge Dimensions
The relationship between the .223 Remington cartridge and the firearm chamber is critical for functionality. The .223 Remington cartridge headspaces on its 23 degree shoulder.
This means the angled portion of the brass casing physically stops against a matching machined angle inside the barrel chamber. Proper case length and shoulder setback are mandatory. If a reloader pushes the shoulder back too far during resizing, the cartridge will sit too deeply in the chamber, potentially causing light primer strikes or dangerous case head separation upon firing.
.223 Remington Dimensions vs Similar Cartridges
To understand the .223 Remington size profile, it is helpful to compare it against other popular rifle cartridges. Note that while some dimensions may appear identical, these cartridges are not interchangeable unless specifically noted by firearm manufacturers.
| Cartridge | Bullet Diameter | Case Length | Overall Length | Base Diameter | Maximum Pressure | Source |
| .223 Remington | .224 in | 1.760 in | 2.260 in | .376 in | 55,000 psi | SAAMI |
| 5.56x45mm NATO | .224 in | 1.760 in | 2.260 in | .376 in | 62,366 psi | NATO |
| .300 Blackout | .308 in | 1.368 in | 2.260 in | .376 in | 55,000 psi | SAAMI |
| .204 Ruger | .204 in | 1.850 in | 2.260 in | .376 in | 57,500 psi | SAAMI |
| .22-250 Rem | .224 in | 1.912 in | 2.350 in | .473 in | 65,000 psi | SAAMI |
| .22 ARC | .224 in | 1.525 in | 2.260 in | .441 in | 52,000 psi | SAAMI |
.223 Remington vs 5.56 NATO Dimensions
The .223 Remington and the 5.56x45mm NATO have perfectly identical external cartridge dimensions. The brass cases and bullet diameters measure exactly the same. However, they are not completely identical in application.
- Chamber Dimensions: The 5.56 NATO firearm chamber is cut with a longer throat or leade. This allows the NATO cartridge to accommodate longer, heavier tracer and armor piercing bullets without jamming them into the rifling. A standard .223 Remington chamber has a shorter throat.
- Pressure Specification: 5.56 NATO ammunition is loaded to higher pressures than commercial .223 Remington.
- Interchangeability: You can safely fire .223 Remington ammunition in a 5.56 NATO chamber. However, firing 5.56 NATO ammunition in a dedicated .223 Remington chamber can result in dangerous pressure spikes due to the shorter throat and higher powder charge.
.223 Remington SAAMI vs C.I.P. Dimensions
Cartridge dimensions and safe pressure limits are governed by SAAMI in the United States and C.I.P. in Europe.
The dimensional specifications for the .223 Remington are functionally identical between the two bodies to ensure global compatibility. However, the way they measure and report pressure differs. SAAMI lists the maximum average pressure for the .223 Remington at 55,000 psi, measured via conformal piezoelectric transducers. C.I.P. lists the maximum pressure for the cartridge at 430 MPa, which is approximately 62,366 psi, using piezoelectric sensors placed at a different location on the case. These are not contradictory figures. They are the result of different testing methodologies and measurement locations. Ammunition loaded to SAAMI specs is safe in C.I.P. proofed rifles.
.223 Remington Bullet Weight And Dimensions
The .223 Remington is widely loaded in several common bullet weights, which directly affect how the cartridge is configured.
- 55 grain: The traditional standard weight. It fits perfectly within the 2.260 inch overall length limit while leaving plenty of case capacity for powder.
- 62 grain: Often used in modern target and hunting loads. The bullet is physically longer, requiring it to be seated slightly deeper into the case.
- 77 grain: A very long, heavy match bullet. To stay under the 2.260 inch maximum magazine length, these bullets must be seated deep into the powder column, which reduces the amount of gunpowder the case can hold.
Bullet weight does not change the standardized brass case dimensions, but a heavier, longer bullet forces the manufacturer to adjust the seating depth to ensure the cartridge still fits in the magazine.
Why .223 Remington Dimensions Matter
Understanding the specific .223 Remington measurements is essential for several practical reasons.
- Headspacing: Because the round headspaces on the 23 degree shoulder, cases that stretch beyond 1.760 inches must be trimmed. If they are not, the case mouth will pinch in the chamber and cause pressure spikes.
- Feeding and Magazine Compatibility: AR-15 magazines are strictly engineered around a 2.260 inch maximum overall length. Ammunition loaded longer than this will bind inside the magazine tube.
- Reloading Data: Because case capacity varies by manufacturer, reloaders must carefully measure their specific brass. Using a maximum powder charge in a case with thick walls and low internal capacity can result in a blown primer or damaged rifle.
Manufacturer Specifications vs Independent Measurements
If you use calipers to measure factory .223 Remington ammunition from companies like Federal, Winchester, or Hornady, the numbers will rarely match the SAAMI maximum specifications exactly.
SAAMI and C.I.P. publish maximum allowable dimensions to ensure safety. Ammunition manufacturers produce their cases slightly smaller than these maximums. For example, measuring a factory cartridge and finding a case length of 1.745 inches or an OAL of 2.240 inches does not mean the ammunition is defective. It simply means the manufacturer built in a reliable tolerance margin to guarantee chambering in dirty or tight rifles.
Common Questions
What are the dimensions of the .223 Remington?
The key maximum dimensions are a bullet diameter of .224 inches, a case length of 1.760 inches, and an overall cartridge length of 2.260 inches.
What is the .223 Remington case length?
The maximum SAAMI case length is 1.760 inches (44.70 mm).
What is the .223 Remington overall length?
The maximum overall length (OAL) is 2.260 inches (57.40 mm).
What is the .223 Remington bullet diameter?
The standard bullet diameter is .224 inches.
What is the .223 Remington rim diameter?
The rim diameter measures .378 inches (9.60 mm).
What is the .223 Remington case diameter?
The case diameter at the base is .376 inches, tapering to a .354 inch shoulder.
What is the difference between .223 bore and bullet diameter?
The bullet diameter is .224 inches, while the barrel bore or land diameter is .219 inches and the groove diameter is .224 inches, allowing the bullet to engage the rifling tightly.
How do .223 Remington and 5.56 NATO dimensions compare?
The external cartridge dimensions are identical. However, the 5.56 NATO uses higher pressures and requires a chamber with a longer throat to safely fire.
What is the maximum overall length of the .223 Remington?
The absolute maximum allowed by SAAMI is 2.260 inches to ensure magazine compatibility.
What is the .223 Remington maximum pressure?
The SAAMI maximum average pressure is 55,000 psi.