The standard .308 Winchester bullet size features a nominal diameter of 0.308 inches, which converts mathematically to approximately 7.82 millimeters. While the diameter remains strictly constant across all .308 Winchester ammunition to ensure barrel compatibility, these projectiles are available in many different weights and structural designs. Because of these distinct variations in weight and aerodynamic profile, the overall bullet length and physical dimensions can vary significantly depending on the specific application.
308 Bullet Size
| .308 Winchester Bullet | Bullet Diameter | Diameter in Millimeters | Bullet Weight | Bullet Weight in Grams | Typical Bullet Length | Bullet Type | Notes |
| 110 grain | 0.308 in | 7.82 mm | 110 gr | 7.13 g | 0.905 in | Varmint / Polymer Tip | Lightweight, short profile |
| 125 grain | 0.308 in | 7.82 mm | 125 gr | 8.10 g | 1.040 in | Soft Point / Polymer Tip | Reduced recoil applications |
| 150 grain | 0.308 in | 7.82 mm | 150 gr | 9.72 g | 1.120 in | FMJ / Soft Point | Common hunting weight |
| 155 grain | 0.308 in | 7.82 mm | 155 gr | 10.04 g | 1.130 in | BTHP / Match | Palma match target shooting |
| 165 grain | 0.308 in | 7.82 mm | 165 gr | 10.69 g | 1.180 in | Soft Point / Bonded | Ideal mid-weight hunting |
| 168 grain | 0.308 in | 7.82 mm | 168 gr | 10.89 g | 1.210 in | BTHP / Match | Standard target shooting |
| 175 grain | 0.308 in | 7.82 mm | 175 gr | 11.34 g | 1.240 in | BTHP / Match | Long-range precision |
| 180 grain | 0.308 in | 7.82 mm | 180 gr | 11.66 g | 1.180 in | Soft Point / Partition | Heavy game hunting |
| 190 grain | 0.308 in | 7.82 mm | 190 gr | 12.31 g | 1.340 in | BTHP / Match | Heavy target shooting |
| 200 grain | 0.308 in | 7.82 mm | 200 gr | 12.96 g | 1.530 in | Polymer Tip Match | Specialized long-range |
| 220 grain | 0.308 in | 7.82 mm | 220 gr | 14.26 g | 1.185 in | Round Nose | Short-range heavy brush |
308 Bullet Size: 0.308 inches (7.82 mm) nominal bullet diameter – Common .308 Winchester bullets vary in weight, length, and design even though they share the same nominal diameter.
What Size Is a 308 Bullet?
The .308 Winchester cartridge uses a bullet with a nominal diameter of 0.308 inches, which equals 7.82 mm. To understand .308 bullet dimensions fully, it is necessary to differentiate the projectile from the barrel and the complete cartridge.
Based on official Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) specifications, these terms indicate different measurements:
- Bullet diameter: The physical measurement of the projectile itself, specified as 0.308 inches.
- Bore diameter: The interior diameter of the rifle barrel measured across the top of the raised rifling lands, specified as 0.300 inches.
- Groove diameter: The interior diameter of the barrel measured from the deepest part of the rifling grooves, specified as 0.308 inches. The bullet must match this diameter to create a proper gas seal.
- Cartridge diameter: The external dimensions of the loaded ammunition round, which vary at different points along the brass case.
- Case diameter: The measurement of the brass casing, which tapers from 0.4703 inches at the base down to 0.3433 inches at the neck.
308 Bullet Diameter in Inches and Millimeters
| Measurement | Inches | Millimeters |
| Nominal .308 bullet diameter | 0.308 | 7.82 mm |
| 7.62 mm | 0.300 | 7.62 mm |
| .308 inch | 0.308 | 7.82 mm |
The designation “7.62” often causes confusion regarding the actual 308 bullet size. A mathematically exact conversion of 7.62 mm yields 0.300 inches. In firearms terminology, 7.62 mm refers to the barrel’s internal bore diameter (the distance between the lands). However, a bullet must be slightly larger than the bore to grip the rifling and form a tight seal. Therefore, the projectile itself is sized to match the groove diameter of the barrel. This requires a bullet measuring 0.308 inches, which mathematically converts to approximately 7.82 mm.
308 Bullet Weight and Size
| Bullet Weight | Weight in Grams | Common Bullet Type | Typical Bullet Design | Notes |
| 110 grain | 7.13 g | V-MAX / Hollow Point | Short bearing surface, polymer tip | Used for varmint hunting |
| 150 grain | 9.72 g | Full Metal Jacket (FMJ) | Standard spitzer boat tail | General purpose target shooting |
| 168 grain | 10.89 g | Boat Tail Hollow Point | Sleek ogive, hollow point | Optimized for 300 to 600 yards |
| 180 grain | 11.66 g | Soft Point Partition | Flat base, exposed lead nose | Deep penetration for large game |
| 220 grain | 14.26 g | Round Nose | Long bearing surface, blunt tip | Designed for maximum energy transfer |
Bullet weight does not directly determine bullet diameter, as all .308 Winchester bullets must remain strictly 0.308 inches wide to safely traverse the barrel. Instead, changes in weight directly impact the overall bullet length. Heavier bullets require more mass, and since the diameter is fixed, manufacturers must make the projectile longer. However, length is also dictated by construction and materials. A 150-grain bullet made of solid copper will be noticeably longer than a 150-grain bullet made of dense lead, because copper is lighter and requires more physical volume to achieve the same weight.
308 Bullet Length
There is no single universal .308 bullet length. Length varies significantly based on weight, shape, and intended application.
| Bullet Weight | Diameter | Bullet Length | Manufacturer | Bullet Type |
| 110 grain | 0.308 in | 0.905 in | Hornady | V-MAX |
| 150 grain | 0.308 in | 1.120 in | Hornady | FMJ-BT |
| 168 grain | 0.308 in | 1.210 in | Sierra | MatchKing BTHP |
| 175 grain | 0.308 in | 1.240 in | Sierra | MatchKing BTHP |
| 180 grain | 0.308 in | 1.180 in | Nosler | Partition Soft Point |
| 220 grain | 0.308 in | 1.185 in | Hornady | InterLock Round Nose |
Bullet profile, ballistic coefficient goals, jacket design, core material, and weight all affect bullet length. A bullet designed for long-range aerodynamics (like a boat tail hollow point) will feature an elongated, sloping nose (ogive) to cut through the air efficiently, making it longer than a blunt round-nose bullet of the exact same weight.
308 Cartridge Dimensions
The .308 Winchester cartridge represents the entire assembled unit of ammunition, whereas the bullet is merely the projectile seated at the top. The official dimensional specifications according to SAAMI are as follows:
| Dimension | .308 Winchester |
| Bullet diameter | 0.308 in (7.82 mm) |
| Case length | 2.015 in max |
| Overall cartridge length | 2.810 in max |
| Case diameter | 0.4703 in (base) |
| Base diameter | 0.4703 in |
| Rim diameter | 0.4728 in |
| Neck diameter | 0.3433 in |
| Shoulder diameter | 0.4539 in |
308 Bullet vs 30 06 Bullet Size
| Specification | .308 Winchester | .30-06 Springfield |
| Nominal bullet diameter | 0.308 in | 0.308 in |
| Diameter in mm | 7.82 mm | 7.82 mm |
| Common bullet weights | 150, 165, 168, 175, 180 gr | 150, 165, 180, 200, 220 gr |
| Typical bullet length | Varies (0.905 in to 1.530 in) | Varies (0.905 in to 1.530 in) |
| Case length | 2.015 in | 2.494 in |
| Overall cartridge length | 2.810 in | 3.340 in |
The .308 Winchester and the .30-06 Springfield shoot the exact same projectiles. Both cartridges use bullets with a nominal diameter of 0.308 inches. The dimensional differences exist entirely within the brass casings. The .30-06 Springfield utilizes a much longer case, resulting in a longer overall cartridge length and greater powder capacity, but the actual 308 bullet size leaving the barrel is identical for both calibers.
308 Bullet vs 223 Bullet Size
| Specification | .308 Winchester | .223 Remington |
| Bullet diameter | 0.308 in | 0.224 in |
| Diameter in millimeters | 7.82 mm | 5.70 mm |
| Common bullet weights | 150 gr, 168 gr, 175 gr | 55 gr, 62 gr, 77 gr |
| Typical bullet length | 1.120 in to 1.240 in | 0.700 in to 0.900 in |
| Case length | 2.015 in | 1.760 in |
| Overall cartridge length | 2.810 in | 2.260 in |
The .308 Winchester is significantly larger than the .223 Remington in every dimension. The .308 bullet diameter measures 0.308 inches (7.82 mm), whereas the .223 bullet diameter measures 0.224 inches (5.7 mm). Due to this size difference, common .308 Winchester bullets weigh nearly three times as much as common .223 Remington bullets.
308 Bullet vs 7.62 NATO Bullet Size
The .308 Winchester and the 7.62×51mm NATO share the same physical bullet size. Both cartridges utilize projectiles with a published SAAMI and CIP nominal diameter of 0.308 inches (7.82 mm). The external dimensions of the two cartridges are functionally identical, allowing them to chamber in the same physical space. However, they are not entirely identical in every specification. The differences lie in the internal case capacity, the brass thickness, and the maximum allowed chamber pressures, rather than the bullet dimensions.
308 Bullet Size vs Other Common Calibers
| Cartridge | Nominal Bullet Diameter | Diameter in mm | Common Bullet Weights |
| .223 Remington | 0.224 in | 5.70 mm | 55, 62, 77 gr |
| .243 Winchester | 0.243 in | 6.17 mm | 85, 95, 100 gr |
| 6.5 Creedmoor | 0.264 in | 6.71 mm | 120, 140, 147 gr |
| .270 Winchester | 0.277 in | 7.04 mm | 130, 140, 150 gr |
| .308 Winchester | 0.308 in | 7.82 mm | 150, 168, 175, 180 gr |
| .30-06 Springfield | 0.308 in | 7.82 mm | 150, 165, 180, 200 gr |
| .300 Winchester Magnum | 0.308 in | 7.82 mm | 180, 190, 200, 220 gr |
308 Bullet Size and Ballistic Coefficient
A bullet’s ballistic coefficient measures how well it overcomes air resistance. Because the .308 bullet diameter is locked at 0.308 inches, manufacturers alter the shape and overall length to improve aerodynamic efficiency.
Two .308 bullets of the exact same diameter and weight can have significantly different ballistic coefficients depending on their profile. A 180-grain round-nose hunting bullet has a short, blunt profile that creates high drag. A 180-grain match bullet features a sharp polymer tip, a long sloping nose, and a tapered boat tail base. While longer and heavier bullets often tend to have higher ballistic coefficients, it is not an automatic rule. A lighter monolithic copper bullet might be longer than a heavier lead bullet, but perform differently in the air due to weight distribution.
Are All 308 Bullets the Same Size?
No, all .308 Winchester bullets are not the same physical size. While they all share a required nominal diameter of 0.308 inches to safely engage the rifling of the barrel, they differ substantially in length, profile, nose shape, jacket construction, core material, ballistic coefficient, and bullet type. A 110-grain varmint bullet is incredibly short and squat compared to a 200-grain long-range match bullet, despite both being exactly 0.308 inches wide.
How Big Is a 308 Bullet?
A standard .308 bullet is exactly 0.308 inches (7.82 mm) in diameter. The complete physical size of the projectile depends entirely on its weight and intended design. A typical 150-grain .308 bullet measures 0.308 inches across and approximately 1.120 inches long, while heavier options like a 175-grain bullet can exceed 1.240 inches in length.
308 Bullet Size FAQs
What size is a 308 bullet?
A .308 bullet has a nominal diameter of 0.308 inches, which is 7.82 millimeters.
What is the diameter of a 308 bullet?
The diameter is 0.308 inches.
How many millimeters is a 308 bullet?
A 308 bullet measures 7.82 millimeters in diameter, even though it is fired from a rifle with a 7.62 millimeter bore diameter.
Is a 308 bullet really 7.62 mm?
No. The barrel’s internal bore diameter is 7.62 mm, but the projectile itself measures 7.82 mm (0.308 inches) so it can grip the rifling grooves tightly.
How long is a 308 bullet?
Bullet length varies by design and weight. A typical 150-grain .308 bullet is around 1.120 inches long, while a 175-grain bullet is roughly 1.240 inches long.
What is the heaviest 308 bullet?
While custom weights exist, the heaviest common .308 Winchester projectiles typically weigh 220 grains.
What is the most common 308 bullet weight?
The 150-grain and 168-grain weights are the most common for hunting and target shooting, respectively.
What bullet weights are available for 308?
Standard .308 Winchester bullet weights range from 110 grains up to 220 grains.
Are .308 and 7.62 bullets the same size?
Yes, both .308 Winchester and 7.62x51mm NATO use projectiles that are exactly 0.308 inches (7.82 mm) in diameter.
Is a 308 bullet bigger than a 223 bullet?
Yes. A 308 bullet measures 0.308 inches (7.82 mm) in diameter, while a 223 bullet measures only 0.224 inches (5.7 mm) in diameter.
Is a 308 bullet the same diameter as a 30 06 bullet?
Yes. Both the .308 Winchester and the .30-06 Springfield fire projectiles with a 0.308-inch diameter.
What is the difference between 308 bullet size and 308 cartridge size?
The 308 bullet size only refers to the metal projectile itself (0.308 inches wide), while the cartridge size refers to the entire loaded round of ammunition, which includes the brass casing and measures up to 2.810 inches in overall length.