The .45-70 Government is a classic straight-walled rimmed rifle cartridge originally designed for military service and later adopted widely for hunting and lever-action sporting platforms.Its core structural measurements include a standard bullet diameter of 0.458 inches (11.6 mm), a maximum case length of 2.105 inches (53.5 mm), and a maximum overall cartridge length (COAL) of 2.550 inches (64.8 mm).The rimmed case features a prominent rim diameter of 0.608 inches (15.4 mm), a base diameter of 0.505 inches (12.8 mm), and a neck diameter of 0.480 inches (12.2 mm). Depending on whether specifications are derived from SAAMI industry standards or historical black-powder guidelines, published figures reflect precise engineering tolerances tailored to ensure safe operation across a diverse range of vintage and modern firearms.
45-70 Government Dimensions
| Dimension | Inches | Millimeters | Specification Type | Source | Notes |
| Bullet Diameter | 0.458 in | 11.6 mm | Nominal / Standard | SAAMI / Military | Standard .45-caliber projectile diameter |
| Case Length | 2.105 in | 53.5 mm | Maximum | SAAMI | Maximum length from case mouth to base |
| Overall Cartridge Length (COAL) | 2.550 in | 64.8 mm | Maximum | SAAMI | Maximum length for lever-action and single-shot actions |
| Rim Diameter | 0.608 in | 15.4 mm | Maximum | SAAMI | Distinct rimmed profile supporting rim headspacing |
| Base Diameter | 0.505 in | 12.8 mm | Maximum | SAAMI | Case body diameter just forward of the rim |
| Neck Diameter | 0.480 in | 12.2 mm | Maximum | SAAMI | Outer diameter of the charged or chamber neck |
| Rim Thickness | 0.070 in | 1.8 mm | Nominal Design | SAAMI | Rim depth supporting extractor and headspace fit |
| Shoulder Geometry | Straight-walled | Straight-walled | Nominal Design | SAAMI | Straight case wall profile with very mild taper |
| Case Capacity | 81.8 gr H₂O | 5.30 ml | Nominal / Usable | SAAMI / Factory | Internal water volume to the case mouth |
| Maximum Pressure | 28,000 psi | 193 MPa | Maximum Average Pressure (MAP) | SAAMI | Standard baseline ceiling (higher for modern rifles) |
Understanding The 45-70 Government Dimensions
Analyzing the specific .45-70 Government dimensions reveals how each measurement governs its performance as a potent, straight-walled big-bore cartridge.
- Bullet Diameter:Standardized at 0.458 inches (11.6 mm), this dimension ensures proper engagement with rifle rifling grooves, accommodating both traditional lead cast bullets and modern jacketed projectiles.
- Case Length: The 2.105-inch maximum case length provides ample internal volume to house heavy charges while fitting traditional rifle actions.
- Rim and Base Diameters: The 0.608-inch rim diameter and 0.505-inch base diameter establish a robust profile designed for positive extraction and reliable rim headspacing.
- Case Wall Geometry:Featuring a straight-walled design with a very minimal taper, the case relies on wall friction and rim contact rather than a shoulder datum for chamber positioning.
- Neck Dimensions & Length: The 0.480-inch neck diameter securely grips the large projectile, maintaining consistent neck tension.
- Overall Cartridge Length (COAL):Bounded at a maximum of 2.550 inches, ensuring reliable feeding through tubular magazines found in classic lever-action rifles.
- Case Capacity:Holding approximately 81.8 grains of water, the massive internal volume accommodates heavy black-powder charges or modern high-performance smokeless loads.
45-70 Government Dimensions In Inches And Millimeters
| Measurement Category | Dimension (Inches) | Dimension (Millimeters) |
| Bullet Diameter | 0.458 in | 11.6 mm |
| Case Length (Max) | 2.105 in | 53.5 mm |
| Overall Cartridge Length (Max) | 2.550 in | 64.8 mm |
| Base Diameter | 0.505 in | 12.8 mm |
| Rim Diameter | 0.608 in | 15.4 mm |
| Neck Diameter | 0.480 in | 12.2 mm |
| Rim Thickness | 0.070 in | 1.8 mm |
45-70 Government Case Dimensions
The .45-70 Government case dimensions define a classic straight-walled, rimmed architecture.The brass case features a maximum length of 2.105 inches, extending uniformly from a base diameter of 0.505 inches up to a neck diameter of 0.480 inches with only a negligible taper.
Because the cartridge headspace is controlled entirely by the rim thickness (nominally 0.070 inches) pressing against the chamber breech, strict adherence to rim and length tolerances is vital. SAAMI guidelines ensure that commercial brass fits smoothly across historic trapdoor springfields, modern single-shots, and robust lever-action rifles.
45-70 Government Bullet Diameter
The official standardized bullet diameter for the .45-70 Government is 0.458 inches (11.6 mm). This dimension applies to standard 405-grain, 500-grain, and modern light-weight hunting projectiles.
It is important to distinguish the 0.458-inch projectile diameter from nominal bore dimensions (historically referred to as .45 caliber across the lands, which measure closer to 0.450 inches).Commercial ammunition strictly utilizes 0.458-inch bullets to guarantee optimal engagement with modern barrel groove depths.
45-70 Government Overall Cartridge Length
The published maximum overall length for the .45-70 Government is 2.550 inches (64.8 mm). This limit is strictly engineered to ensure flawless feeding and cycling through the internal and tubular magazines of lever-action rifles.
Actual loaded cartridge lengths frequently vary based on bullet design—such as flat-nose bullets required for tubular magazines versus pointed or polymer-tipped FTX projectiles—while remaining at or below the 2.550-inch ceiling to prevent action binding.
45-70 Government Case Capacity
The .45-70 Government case capacity is officially documented at approximately 81.8 grains of water.This substantial volume reflects its historical origin as a cartridge designed to house 70 grains of black powder alongside a heavy lead bullet.
When loaded with modern smokeless propellants, this large capacity requires careful powder selection to avoid dangerous over-pressure situations, especially when differentiating between loads intended for fragile antique firearms versus modern robust actions.
45-70 Government Dimensions vs Similar Cartridges
Comparing the .45-70 Government with other straight-walled and big-bore cartridges highlights its distinct geometric footprint.
| Cartridge | Bullet Diameter | Case Length | Overall Length | Rim / Base Diameter | Case Capacity | Source |
| .45-70 Government | 0.458 in | 2.105 in | 2.550 in | 0.608 / 0.505 in | 81.8 gr H₂O | SAAMI |
| .450 Bushmaster | 0.452 in | 1.700 in | 2.260 in | 0.473 / 0.500 in | ~59.5 gr H₂O | SAAMI |
| .44-40 WCF | 0.427 in | 1.305 in | 1.592 in | 0.525 / 0.471 in | ~40.0 gr H₂O | SAAMI |
| .30-06 Springfield | 0.308 in | 2.494 in | 3.340 in | 0.473 in | 68.2 gr H₂O | SAAMI |
| .454 Casull | 0.452 in | 1.383 in | 1.765 in | 0.512 / 0.456 in | ~38.0 gr H₂O | SAAMI |
45-70 Government vs .450 Bushmaster Dimensions
Comparing the .45-70 Government to the modern .450 Bushmaster reveals distinct cartridge layout philosophies. While both fire large-caliber projectiles (.458 in vs .452 in), the .45-70 features a much longer case length (2.105 in vs 1.700 in) and a significantly larger rim diameter (0.608 in vs 0.473 in).
The .45-70 provides greater case capacity (~81.8 gr vs ~59.5 gr) and is optimized for rimmed lever-action and single-shot rifles, whereas the .450 Bushmaster is a rebated-rim cartridge engineered specifically to feed through standard AR-15 magazine wells.
45-70 Government vs .44-40 WCF Dimensions
The .44-40 WCF is another historic lever-action cartridge, but it is noticeably smaller than the .45-70 Government. The .45-70 features a longer case (2.105 in vs 1.305 in) and a larger base diameter (0.505 in vs 0.471 in), yielding more than double the powder capacity (~81.8 gr vs ~40 gr).
Furthermore, the .45-70 fires a wider 0.458-inch bullet compared to the 0.427-inch projectile of the .44-40, reflecting its status as a full-power military rifle round rather than an intermediate cartridge.
45-70 Government Chamber And Cartridge Dimensions
Chamber specifications for the .45-70 Government are designed around rim headspacing. Because the case is straight-walled, the chamber locks off the 0.070-inch rim thickness against the breech face rather than relying on a shoulder or belt.
Proper headspace ensures that the case does not stretch excessively during firing. Gunsmiths and manufacturers utilize precise SAAMI reamer tolerances to ensure smooth chambering across vintage museum pieces and modern custom rifles alike.
45-70 Government Bullet Weight And Dimensions
Factory loads and handloads for the .45-70 Government encompass a wide variety of projectile weights, most commonly including 300-grain, 325-grain, 405-grain, and heavy 500-grain options.
While bullet weight does not alter baseline case dimensions, projectile length and nose profile directly impact overall cartridge length. Handloaders must ensure that loaded ammunition meets the 2.550-inch maximum length requirement to function correctly in lever-action tubular magazines.
Why 45-70 Government Dimensions Matter
Understanding exact cartridge dimensions is essential for several practical reasons:
- Chamber Fit & Safety: Ensures commercial ammunition matches reamer specifications safely across different firearm generations.
- Headspacing: Guarantees proper rim contact and prevents excessive case separation.
- Magazine Compatibility: Confirms that loaded rounds comply with overall length limits for smooth cycling in lever-action rifles.
- Reloading Precision: Guides correct resizing die setup and powder charge scaling for specific pressure tiers.
Manufacturer Specifications vs Independent Measurements
Official dimensions for the .45-70 Government are standardized globally by SAAMI.
While commercial ammunition and modern brass adhere strictly to these engineering blueprints, independent measurements of vintage military brass or specialized cast bullets can reveal minor dimensional variances. Official standards remain the definitive benchmark for firearm manufacturing, chamber reamer design, and pressure testing compliance.
Common Questions
What are the dimensions of 45-70 Government?
The .45-70 Government features a bullet diameter of 0.458 in, a case length of 2.105 in, a maximum overall length of 2.550 in, a base diameter of 0.505 in, and a rim diameter of 0.608 in.
What is the 45-70 Government case length?
The maximum case length is 2.105 inches (53.5 mm).
What is the 45-70 Government overall length?
The maximum overall cartridge length (COAL) is 2.550 inches (64.8 mm).
What is the 45-70 Government bullet diameter?
The standard bullet diameter is 0.458 inches (11.6 mm).
What is the 45-70 Government rim diameter?
The rim diameter is 0.608 inches (15.4 mm).
What is the 45-70 Government base diameter?
The base diameter is 0.505 inches (12.8 mm).
What is the 45-70 Government case capacity?
The nominal case capacity is approximately 81.8 grains of water.
How does 45-70 Government compare with .450 Bushmaster dimensions?
The .45-70 features a longer case (2.105 in vs 1.700 in) and a larger rim (0.608 in vs 0.473 in) with greater powder capacity (~81.8 gr vs ~59.5 gr), whereas the .450 Bushmaster is engineered for AR-15 magazines.
What is the maximum pressure for 45-70 Government?
The SAAMI Maximum Average Pressure (MAP) baseline is 28,000 psi, though modern robust rifles safely handle higher specialized pressure tiers.
Final Verdict
The .45-70 Government is defined by its 0.458-inch bullet diameter, 2.105-inch case length, and 2.550-inch maximum overall length, establishing a timeless straight-walled rimmed profile.Its robust 0.608-inch rim diameter and massive ~81.8-grain case capacity allow it to deliver heavy-hitting energy across historical and modern platforms. Understanding its precise dimensional specifications, rim headspacing requirements, and pressure limits is essential for safe shooting, accurate reloading, and optimal firearm performance.