.284 Winchester
The.284 Winchester (7.21x55mmRB) is a rebated rim rifle cartridge 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.
.284 Winchester

Google Books - (1898). " Advertisements ". The American Monthly Review of Reviews: p. 49. New York: The Review of Reviews Co.. · Public domain
- Field
- rifle cartridge.
- Period
- 1963.
- Region
- United States.
VALÉORINE Encyclopedia
VALÉORINE documentary reading
Documentary summary
The.284 Winchester (7.21x55mmRB) is a rebated rim rifle cartridge 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.
Admitted source layer · organised and presented by VALÉORINE
Note VALÉORINE
No house-authored Note is published until its assertions and sources pass the VALÉORINE evidence contract. The documentary article remains available in full while that enrichment is being consolidated.
Documentary enrichment in progress · no unsupported statement published
Reference Check
Propose documentary evidence for .284 Winchester. A contribution is never written directly as fact: identity, source, rights and evidence gates still decide.
Sign in to contribute
World of VALÉORINE
Documentary connections
Only confirmed graph relationships appear here. Images are shown only when their identity and reuse rights both pass the documentary gate.
Documentary evidence
Evidence Panel
not yet certified
- Identity
- resolved
- Independent source families
- 0
- Admitted assertions
- 0
- Open conflicts
- 0
Authority files
wikidata · Q4545235 · wikipedia · .284 Winchester
In this article
History
History
Winchester has continued to produce brass cases for this cartridge since 1963.
The Savage Model 99 lever-action, Winchester Model 100 autoloader, Winchester Model 88 lever-action, and Ruger Ruger M77 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-inch caliber to allow for the use of the bolt faces common to the 7.92×57mm Mauser and its many derivatives.
Cartridge dimensions
Cartridge dimensions
The.284 Winchester has 4.29 mL (66 grains H2O) 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 twist rate 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 pressure limit for the.284 Winchester is 56,000 PSI (386 MPa).
Contemporary use
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 cartridge is sometimes used for long-range target shooting disciplines such as F-Class, where participants typically handload their ammunition. For this application the.284 Winchester is generally loaded with heavy for caliber very-low-drag bullets. The.284 Winchester is not popular in Europe, where it competes with the ballistically similar 7×64mm. 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
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 the.22-284, 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, and the extremely similar (in the US considered a "Wildcat cartridge" 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 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.
From left to right: metric/imperial ruler for size comparisons next to.308 Winchester,.284 Winchester and 7mm Remington Magnum cartridges loaded with soft point bullets.
Ultratone85
Chronology
Dated record
Chronology
The full dated record · 2 entries
1963
284 Winchester first recorded.
1963
284 Winchester is recorded from 1963.
Primary material
Documents and archives
reference work
- “.284 Winchester”, English Wikipedia, consulted as further reading
Reputable secondary · Wikipedia
institutional register
- Wikidata, structured authority record Q4545235:.284 Winchester
Unverified · Wikimedia Foundation
Notes from the source article
Cited by Wikipedia
Notes from the source article
These works are cited by the source article, in its own numbering. They are recorded as its citations, not as sources VALÉORINE has verified.
- 1.".284 Winchester data" from Accurate Powder
- 2.7mm Accuracy Cartridges - .284 Winchester at www.accurateshooter.com
- 3.C.I.P. decisions, texts and tables free current C.I.P. CD-ROM version download (ZIP and RAR format)
- 4.The .284 Winchester by Chuck Hawks
- 5.What's Wrong With .30 Caliber? By Bryan Litz
- 6.NOLASCO C.I.P. TDCC datasheet 30-284 NOLASCO
- 7.- 284 Win. C.I.P. TDCC datasheet 30 - 284 Win.
- 8.McPherson, M.L. Wildcatting the .284 Winchester Long-range shooters and wildcatters have kept the .284 alive. Rifle Shooter Magazine.
- 9..284 Winchester.
References
Citations
References
Each reference names the institution holding it, so a reader may go to the document itself.
reference work
Partially resolvedinstitutional register
Wikidata, structured authority record Q4545235:.284 WinchesterWikimedia Foundation
Unverified
Connections
Knowledge graph
Connections
Each connection was recorded deliberately, with the basis for it kept on the internal record.
Broader subject
1- rifle cartridgeTerminology
Established from a fact already recorded on a verified source.
The Encyclopedia exists whether or not anything is for sale. Corrections are recorded rather than overwritten, and every version of this record is kept. Published 14 August 2026.
Elsewhere in Militaria
6,095 published records in this field, each with its sources named.
- .277 WolverineTerminology
- .280 BritishTerminology
- .280 RemingtonTerminology
- .280 RossTerminology
- .297/230 MorrisTerminology
- .297/250 RookTerminology
- .30 carbineTerminology
- .30 NewtonTerminology
Best supported in this field
For owners
Own an object connected with .284 Winchester?
A specialist will read what you send and tell you what the house can establish, what it cannot, and whether the object is suited to sale. There is no charge and no obligation. The object stays with you throughout; nothing is shipped to us unless it is arranged in writing beforehand.