The .284 Winchester (7.21x55mmRB) is a rebated rim
rifle cartridge
A rifle cartridge is a firearm cartridge (firearms), cartridge primarily designed and intended for use in a rifle/carbine, or machine gun.
Types Full-powered
A full-powered cartridge is a rifle cartridge used interchangeably between servic ...
introduced by the Winchester Repeating Arms Company in 1963.
The .284 Winchester was designed to duplicate the performance of the
.270 Winchester and
.280 Remington cartridges from the new
Winchester Model 100 autoloader and
Winchester Model 88 lever-action rifles. The result was a
7 mm cartridge of comparable overall length to the
.308 Winchester with greater case capacity and power potential.
.284 Winchester has enjoyed a resurgence due to interest from long-range competitive shooters. Winchester has continued to produce brass cases for this cartridge since 1963.
History
The
Savage Model 99
The Savage Model 99, Model 1899, and their predecessor the model 1895 are a series of hammerless lever action rifles created by the Savage Arms Company in Utica, New York. The Model 99 family featured a unique rotary magazine, and later added so ...
lever-action,
Winchester Model 100 autoloader,
Winchester Model 88 lever-action, and Ruger
Ruger M77
The Ruger M77 is a bolt-action rifle produced by Sturm, Ruger & Co. It was designed by Jim Sullivan during his three years with Ruger. It was designed primarily as a hunting rifle featuring a traditional Mauser K98-style two-lugged bolt with a ...
rifles were chambered in the .284 Winchester.
The
7.5x55 Swiss provided inspiration for the cartridge, with the bullet diameter reduced to 7mm and the rim rebated to .473” to allow for the use of the bolt faces common to the
7.92×57mm Mauser and its many derivatives.
Cartridge dimensions
The .284 Winchester has 4.29
ml (66
grains
A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and le ...
H
2O) of cartridge case capacity. The case has a rebated rim and a body diameter nearly as large in diameter as the
.375 H&H Magnum and its derivatives.
''.284 Winchester maximum C.I.P. cartridge dimensions'' All sizes in millimeters (mm).
American conventions define the shoulder angle at alpha/2 = 35 degrees. The common
rifling
Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such groov ...
twist rate
Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such groov ...
for this cartridge is 254 mm (1 in 10 in), 6 grooves, Ø lands = 7.00 mm, Ø grooves = 7.19 mm, land width = 2.79 mm and the
primer type is large rifle.
According to the official
C.I.P. guidelines, .284 Winchester specifications call for a 440 MPa (63,816 psi) piezo pressure. In C.I.P. regulated countries, firearms chambered in any given cartridge must be
proofed at 125% of the maximum C.I.P. pressure to certify sale to consumers.
The
SAAMI
The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI, pronounced "Sammy") is an association of American manufacturers of firearms, ammunition, and components. SAAMI is an accredited standards developer that publishes several A ...
pressure limit for the .284 Winchester is 56,000
PSI
Psi, PSI or Ψ may refer to:
Alphabetic letters
* Psi (Greek) (Ψ or ψ), the twenty-third letter of the Greek alphabet
* Psi (Cyrillic), letter of the early Cyrillic alphabet, adopted from Greek
Arts and entertainment
* "Psi" as an abbreviat ...
(386 MPa).
Contemporary use
The .284 Winchester is ballistically similar to the .280 Remington with equivalent bullet weights. Aside from Winchester, no major company has loaded factory ammunition for the .284 Winchester.
[The .284 Winchester by Chuck Hawks](_blank)
/ref>
The cartridge is sometimes used for long-range target shooting disciplines such as F-Class, where participants typically handload
Handloading, or reloading, is the practice of making firearm cartridges by manually assembling the individual components ( metallic/ polymer case, primer, propellant and projectile), rather than purchasing mass-assembled, factory-loaded com ...
their ammunition. For this application the .284 Winchester is generally loaded with heavy for caliber very-low-drag bullet
A very-low-drag bullet (VLD) is primarily a small arms ballistics development of the 1980s–1990s, driven by the design objective of bullets with higher degrees of accuracy and kinetic efficiency, especially at extended ranges. To achieve this, ...
s.
The .284 Winchester is not popular in Europe, where it competes with the ballistically similar 7×64mm
The 7×64mm (also unofficially known as the 7×64mm Brenneke, though its designer's name was never officially added as a part of the cartridge name) is a rimless bottlenecked centerfire cartridge developed for hunting. As is customary in Euro ...
. When compared to the .284 Winchester, the 7×64mm has a lower C.I.P. maximum allowed chamber pressure and a slightly larger bore. European 7 mm cartridges feature 7.24 mm (0.285 in) grooves Ø diameter, while American 7 mm cartridges have 7.21 mm (0.284 in) grooves Ø.
Wildcats
While the .284 Winchester has occasionally been chambered in factory rifles, the chief reason for its survival is wildcatting. Wildcats are not governed by C.I.P. or SAAMI rules so wildcatters can capitalize on achievable high operating pressures. With the .284 Winchester as the parent case wildcatters have created 6mm-284, 6.5mm-284, .284 Shehane, .30-284, .338-284, .35-284, .450 Bushmaster and the .375-284 variants and the .475 Wildey Magnum pistol cartridge.
In those countries where restrictions prevent civilian use of firearms chambered in a military cartridge, the .30-284 wildcat has been a favored option to convert military surplus rifles. Russian Mosin–Nagant and Swiss Schmidt–Rubin rifles, as well as 7.5×54 French MAS caliber rifles may be rechambered. The easiest way to do this is to rechamber the firearm to something that uses the same barrel bore, such as .30 cal. or 7.62 mm, but completely removes the old chamber during the process. The C.I.P. has recognized and registered both the 30-284 NOLASCO,[NOLASCO C.I.P. TDCC datasheet 30-284 NOLASCO](_blank)
/ref> and the extremely similar (in the US considered a "Wildcat cartridge
A wildcat cartridge, often shortened to wildcat, is a custom-made cartridge (weaponry), cartridge for which ammunition and/or firearms are not mass-produced. These cartridges are often created as experimental variants to optimize a certain ballis ...
" based on the .284 Winchester) 30-284 Win. Both these chamberings completely remove the original 7.5×54mm MAS chamber. They also both have the same C.I.P. pressure ratings as the 7.62×54mm MAS cartridge but differ in their overall length due to the length of the bullet - the NOLASCO carrying a longer bullet for better feeding and an improved ballistic coefficient, and to meet a somewhat more common European overall length of 76 mm, the same as the 7.5x54mm French and very close to the 7.5×55mm Swiss.
In terms of popularity, the 6.5-284 Norma cartridge has likely exceeded its parent case. This former wildcat, made by necking down the original Winchester .284 casing to 6.5mm (.264), was developed for long range target shooting where participants usually handload their ammunition. At that time, it was one of the most used non-wildcat cartridges by match shooters in F-Class and 1000 yd/m benchrest
Benchrest shooting is a shooting sport discipline in which accuracy and precision, high-precision rifles are rested on a table or countertop, benchrather than being carried in the shooter's handswhile shooting at shooting target, paper or steel ...
long range competitions. In 2022, because of advancements in high BC 7mm bullet designs, the original Winchester .284 case has made a comeback as the most preferred cartridge in F-class competitions with other .284 caliber (7mm) cartridge variants being wildcatted off the venerable original design (e.g., .284 KMR, .284 Shehane, .284 Wheeler, .284 Ackley Improved).
Many owners of old Swiss service rifles in the United States are also now reforming .284 Winchester cartridge cases up to produce results analogous to the more expensive 7.5×55mm Swiss GP11 cartridge.
The Finnish cartridge company Lapua started making .284 Winchester brass (Product No. 4 PH 7284), again, since Spring 2021.
See also
* 7mm-08 Remington
The 7mm-08 Remington is a rifle cartridge that is almost a direct copy of a wildcat cartridge developed around 1958 known as the 7mm/308. As these names would suggest, it is the .308 Winchester case necked down to accept 7 mm (.284) bullets wit ...
* 7×57mm Mauser
The 7×57mm Mauser (designated as the 7 mm Mauser or 7×57mm by the SAAMI and 7 × 57 by the C.I.P.) is a first-generation smokeless powder rimless bottlenecked rifle cartridge. It was developed by Paul Mauser of the Mauser company in ...
* 7×64mm
The 7×64mm (also unofficially known as the 7×64mm Brenneke, though its designer's name was never officially added as a part of the cartridge name) is a rimless bottlenecked centerfire cartridge developed for hunting. As is customary in Euro ...
* 7 mm Remington Magnum
The 7mm Remington Magnum rifle cartridge was introduced as a commercially available round in 1962, along with the new Remington Model 700 bolt-action rifle. It is a member of the belted magnum family that is directly derived from the venerable ...
* List of rebated rim cartridges
Below is a list of rebated rim cartridges. Rebated-rim cartridges have a rim that is significantly smaller in diameter than the base of the case, serving only for extraction. Functionally the same as a rimless case, the rebated rim allows a gun t ...
* List of rifle cartridges
List of rifle cartridges, by primer type, Caliber, calibre and name.
File:Cartridge Sample 2.jpg, 350px, From left to right: 1 .17 Hornady Mach 2, 2 .17 Hornady Magnum Rimfire, 3 .22 Long Rifle, 4 .22 Winchester Magnum Rimfire, 5 .17/23 SMc, 6 5mm ...
* Table of handgun and rifle cartridges
This is a table of selected pistol/submachine gun and rifle/machine gun cartridges by common name. Data values are the highest found for the cartridge, and might not occur in the same load (e.g. the highest muzzle energy might not be in the same ...
* Delta L problem
Delta commonly refers to:
* Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet
* D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet
* River delta, at a river mouth
* Delta Air Lines, a major US carrier
...
References
External links
.284 Winchester in 7mm Cartridge Guide by AccurateShooter.com
{{DEFAULTSORT:284 Winchester
Pistol and rifle cartridges
Rebated rim cartridges
Winchester Repeating Arms Company cartridges