The term express was first applied to hunting rifles and ammunition beginning in the middle 19th century, to indicate a rifle or ammunition capable of higher than typical velocities. The early express cartridges used a heavy charge of black powder to propel a lightweight, often hollow point bullet, at high velocities to maximize point blank range. Later the express cartridges were loaded with nitrocellulose based gunpowder, leading to the Nitro Express cartridges, the first of which was the .450 Nitro Express.
The term express is still in use today, and is applied to rifles, ammunition, and a type of iron sight. With the widespread adoption of small bore, high velocity rifle cartridges, the meaning of express has shifted in modern usage, and refers to high velocity, large bore rifles and ammunition, typically used for hunting large or dangerous game at close range.
The name originates with a rifle built by James Purdey in 1856 (based on a pattern established a year earlier by William Greener) and named the Express Train, a marketing phrase intended to denote the considerable velocity of the bullet it fired. It was not the first rifle or cartridge of this type but it was Purdy's name express that stuck.
To understand the context of the express cartridge, it is necessary to go back to the weapons that preceded them. Early hunting firearms were typically smoothbore, usually firing a spherical projectile. This meant that a given bore size must fire a given weight of projectile, which put significant limits on the external and terminal ballistics of the gun. The significant arc of the slow round ball limited the maximum point blank range to very short distances, and the spherical nature of the ball required a large bore diameter to carry a ball large and heavy enough to provide a quick kill on large game. These early smoothbore guns were typically measured by gauge, as most modern shotguns still are, rather than by caliber. Typical gauges used ranged from 12 to 4; the 4 gauge, used for large game, fired a massive ball of 1500 grains weight (97 g).
In the 19th century, rifled firearms increasingly gained popularity, and the cylindrical (conical) bullet was introduced. This allowed a wide range of bullet weights to be used with a single bore size; the .450 Black Powder Express, for example, was loaded with bullets ranging from a 270 grain hollow point bullet for small game such as deer, to a 360 grain solid bullet for use on dangerous game, to even heavier hardened bullets for use on elephant. The early black powder express cartridges used paper patched lead bullets, to prevent lead buildup in the bore at the high velocities. These bullets were made of soft lead, and even in solid form they expanded readily and provided great killing power.
Typically the trajectory height would not be greater than 4.5 inches at 150 yards (140 m) and the rifle would have a muzzle velocity of at least 1,750 feet per second (533 m/s). While 1,750 ft/s (533 m/s) is not fast by modern standards, it was in the era of black powder and spherical balls. As nitro powders were introduced and became the standard, bores grew smaller, and velocities grew ever larger, until the term express grew to mean something different than just high velocity. William Greener, for example, splits British sporting rifles at the turn of the 20th century into four classes:
- Large bore smoothbores, or Elephant guns
- Medium bore high velocity rifles, the express rifle
- Small bore, higher velocity rifles, the long range express rifle
- Miniature, short range rifles, or Rook rifles
Since then, express has gradually changed to denote a large bore diameter combined with high velocity. The 1911 Encyclopædia Britannica, for example, lists express cartridges ranging from .360 to .577 caliber. The traditional express rifles were break action designs, either single or double barrel designs, and express rifles are still made in this form today. With the advent of repeating actions, many bolt action rifles were chambered in express cartridges, and often the same cartridge will be found in "flanged" and "rimless" form, the flanged for break-open actions, and the rimless for easier feed from a bolt action rifle's magazine.
Many modern rifle cartridges fire large caliber, heavy bullets at velocities of well over 2,000 feet per second (600 m/s), and the designation express has largely been replaced by Magnum in most cartridge names, though the Nitro Express does live on, with the 1988 introduction of the .700 Nitro Express. With a few exceptions, such the .242 Rimless Nitro Express from the 1920s, and a brief period around 1980 when Remington renamed their .280 Remington cartridge the 7 mm Express Remington, the label express is today used for short range, big game rifles pushing large, fast bullets.
Another item to bear the name express is the iron sight combination, used by William Greener and still found on express rifles today, consisting of a bead front sight and shallow "V" rear sight. The large, usually white bead is easily seen in low light and the shallow "V" notch provides an unobstructed view of the surrounding area.
Traditional express cartridges tend to be long cases, working at low pressures. This is partially due to their black powder roots, but the low pressure cases are also more reliable under extreme conditions, such as found in African hunting. Modern designs may use the belted magnum design; older ones may be rimmed for break actions or rimless for bolt action rifles. The bullets were typically short, light, hollow point designs intended for maximum velocity and ranges out to the maximum point blank range with fixed sights. Early cartridges were loaded with black powder, and many later converted to cordite or other smokeless powders, often yielding two similar cartridges with different loadings, such as the .450 Black Powder Express and the .450 Nitro Express. Older express cartridge ballistics are fairly similar to modern shotgun slug ballistics, while modern big game cartridges, such as the .577 Tyrannosaur and the .587 Nyati, provide ballistics that push the physical limits of the hunter with their tremendous power and recoil.
There are many different express rounds, especially around the .450 size. The proliferation stemmed from a blanket restriction on the importation of .450 ammunition into India intended to prevent arms reaching rebellious natives.
- .375 H&H (Holland and Holland),
- .458 Winchester Magnum, a post WW2 modern round of similar performance to the .450 Nitro Express;
- .460 Weatherby Magnum,
- Nitro Express series including the .577 and .600 NE.
Rifle design 
Express rifles historically came in two actions, singles (single shot) and doubles. The side by side double was among the earliest, but by the early 20th century the bolt action began to replace it. The side by side has two barrels and either single or double triggers. Most parts of the mechanism that fire the gun are duplicated. In the unlikely event that a mechanical failure such as a broken spring or firing pin should occur, the hunter can still fire the second barrel. This design allows the hunter to fire two shots rapidly—the second shot used when the animal is missed or not stopped with the first. If the hunter were using a bolt action rifle, he would have to work the bolt, taking additional time and possibly affecting the aim. Bolt action rifles for hunting typically have a small magazine of about five rounds rather than the ten, thirty, or more found on more modern rifles firing smaller rounds.
Express rifles are generally either single shot or bolt action designs. Doubles are still made but are quite expensive; getting both barrels to shoot to the point of aim is a labor intensive process. Single shot rifles are not often used when hunting dangerous game because follow up shots are not made as quickly. Single shot express rifles, such as the Ruger No. 1 Tropical, are more compact than bolt actions, but while they can weigh less, reduced weight tends to increase felt recoil. Lighter rifles are more likely to be in the hunter's hands, ready for a quick shot when game is found.
See also 
- John Henry Walsh (1871). British Rural Sports, Comprising Shooting, Hunting, Coursing, Fishing, [etc.] Frederick Warne and Co. p. 109.
- William Wellington Greener (1907). The Gun and Its Development.
- "Definition of express rifle". Dictionary.com.
- Thomas Francis Fremantle, Thomas Francis Fremantle Cottesloe (1901). The Book of the Rifle.
- Frank C. Barnes, ed. Stan Skinner. Cartridges of the World, 10th Ed. Krause Publications. ISBN 0-87349-605-1.
- "Definition for "express sights"".
- Randy D. Smith. "Slug Guns - The More I Use Them, the More I Like Them".