| .450/400 3 inch Black Powder Express | |
| Origin: | United Kingdom |
| Type: | Rifle |
| Design Date: | 1880s |
| Parent: | .450 Black Powder Express |
| Case Type: | Rimmed, bottleneck |
| Bullet: | .405 |
| Neck: | .432 |
| Shoulder: | .502 |
| Base: | .544 |
| Rim Dia: | .615 |
| Rim Thick: | .040 |
| Case Length: | 3.25 |
| Length: | 3.85 |
| Primer: | Kynoch # 40 |
| Bw1: | 270 |
| Btype1: | Lead |
| Vel1: | 1850 |
| En1: | 2050 |
| Balsrc: | Barnes & Kynoch. |
| .450/400 2 inch Black Powder Express | |
| Case Length: | 2.375 |
| Bw1: | 270 |
| Btype1: | Lead |
| Vel1: | 1650 |
| En1: | 1630 |
| Balsrc: | Barnes. |
The .450/400 Black Powder Express cartridges were black powder rifle cartridges introduced in the United Kingdom in the 1880s.
The .450/400 Black Powder Express cartridges are bottlenecked centerfire black powder express rifle cartridges produced in two case lengths, 2 inches (60.3 mm) and 3 inches (83 mm). Both cartridges were later loaded as "Nitro for Black" cartridges, the same cartridges loaded with mild loadings of cordite carefully balanced through trial to replicate the ballistics of the black powder versions.
The .450/400 2 inch Black Powder Express was loaded with a bullets from NaNgr driven by NaNgr of black powder. The .450/400 2 inch Nitro for Black was loaded with a jacketed 270 grain round nose bullet driven by 38gr of cordite.
The .450/400 3 inch Black Powder Express was loaded with a bullets from NaNgr driven by 110gr of black powder. The .450/400 3 inch Nitro for Black was loaded with bullets of NaNgr driven by NaNgr of cordite.
The .450/400 Black Powder Express cartridges served as the parent cases for the .450/400 Nitro Express cartridges, the same cartridge cases loaded with greater loads of cordite and heavier bullets to produce far more powerful rounds.
The .450/400 Black Powder Express in both cartridge lengths were developed in the 1880s by necking down the .450 Black Powder Express, the .450/400 2 inch Black Powder Express simply a shortened version. The .450/400 3 inch Black Powder Express was listed in the Kynoch catalogue of 1884 as the .450 reduced to . 400.
Whilst obsolete, .450/400 3 inch Black Powder Express ammunition can still be purchased from ammunition manufacturers such as Kynoch.
The .450/400 Black Powder Express in both case lengths were considered good deerstalking cartridges and was usually chambered in a lightweight stalking rifle.