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.284 Winchester

January 01, 1970

The .284 Winchester (7.21x55mmRB) is a rebated rim firearm cartridge, introduced by Winchester in 1963.

.284 Winchester
.284 Winchester (center) with .308 Win (left) and 7mm Remington Magnum (right)
TypeRifle
Place of originUnited States
Production history
DesignerWinchester
Designed1963
ManufacturerWinchester
Produced1963–present
Specifications
Case typerebated rim, bottleneck
Bullet diameter7.21 mm (0.284 in)
Land diameter7.00 mm (0.276 in)
Neck diameter8.13 mm (0.320 in)
Shoulder diameter12.06 mm (0.475 in)
Base diameter12.72 mm (0.501 in)
Rim diameter12.01 mm (0.473 in)
Rim thickness1.37 mm (0.054 in)
Case length55.12 mm (2.170 in)
Overall length71.12 mm (2.800 in)
Case capacity4.29 cm3 (66.2 gr H2O)
Rifling twist254 mm (1 in 10 in)
Primer typeLarge rifle
Maximum pressure (C.I.P.)440.00 MPa (63,817 psi)
Maximum pressure (SAAMI)386 MPa (56,000 psi)
Ballistic performance
Bullet mass/type Velocity Energy
100 gr (6 g) HDY 100 HP 3,175 ft/s (968 m/s) 2,238 ft⋅lbf (3,034 J)
120 gr (8 g) SPR 120 SP 2,968 ft/s (905 m/s) 2,347 ft⋅lbf (3,182 J)
139 gr (9 g) HDY 139 SP 2,845 ft/s (867 m/s) 2,498 ft⋅lbf (3,387 J)
150 gr (10 g) Super-X Power-Point 2,860 ft/s (870 m/s) 2,724 ft⋅lbf (3,693 J)
Test barrel length: 24 in (610 mm)
Source(s): Winchester Ammunition Accurate Powder [1]

The .284 Winchester was designed to achieve .270 Winchester and .280 Remington performance from the new Winchester Model 100 autoloader and Winchester Model 88 lever-action rifles. The result was a 7 mm cartridge with about the same overall length as the .308 Winchester but with a wider body, that yields a powder capacity about the same as that of the .270 Winchester and .280 Remington.[citation needed]

.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.[2]

History edit

The Savage Model 99 lever-action, Winchester Model 100 autoloader and Winchester Model 88 lever-action rifles were available in .284 Winchester, and Ruger produced a small run of Ruger M77 rifles in this caliber. Ultra Light Arms still builds Model 20 rifles in .284 Winchester.

Cartridge dimensions edit

The .284 Winchester has 4.29 ml (66 grains H2O) of cartridge case capacity. The case has a rebated rim and a body almost as large in diameter as that of typical belted magnum cases.

 

.284 Winchester maximum C.I.P. cartridge dimensions All sizes in millimeters (mm).[3]

Americans would 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 the .284 Winchester case can handle up to 440 MPa (63,816 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers.
The SAAMI pressure limit for the .284 Winchester is set at 56,000 PSI (386 MPa).[1]

When the cartridge over all length is maintained, deeper-seating is necessary with long heavier bullets. This reduces usable powder capacity and hence performance compared to longer-action cartridges like the .280 Remington.

The American .280 Remington cartridge has probably the closest ballistics to the .284 Winchester. The .280 Remington has a lower 405 MPa (58,740 psi) C.I.P maximum allowed chamber pressure and slightly more case capacity.

Contemporary use edit

For open-country hunting of deer and pronghorn, the .284 Winchester loaded with the Speer 130-grain (8.4 g) spitzer at 3,100 ft/s (940 m/s) is adequate, even in a short-action rifle. Larger game calls for bullets weighing from 150 to 160 grains (10 g). H4831, H450, H4350, H414, IMR-4350, and IMR-4831 are excellent powders.[4]

These ballistics show that the .284 Winchester is as good as the .280 Remington with the same weight bullet. The short mountain rifles for which the .284 Winchester seems best suited seldom come with 24-inch barrels. Aside from Winchester, no other major company has ever loaded factory ammunition for the .284 Winchester.[4]

The cartridge is sometimes used for long-range target shooting like F-Class and 1,000 yd/m long range competitions, where participants usually handload their ammunition. For this application the .284 Winchester is loaded with 175 and 180 gr very-low-drag bullets.[5]

The .284 Winchester is not popular in Europe, where it competes with the 7×64mm, to which it is almost ballistically identical. When compared to the .284 Winchester the 7×64mm has a lower C.I.P. maximum allowed chamber pressure and, as a European 7 mm cartridge, has a slightly larger bore. European 7 mm cartridges all have 7.24 mm (0.285 in) grooves Ø diameter. American 7 mm cartridges have 7.21 mm (0.284 in) grooves Ø.

Wildcats edit

Main article: Wildcat cartridge

While it has been occasionally factory chambered in various rifles, the chief reason for its survival has always been 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,[6] and the extremely similar (in the US considered a "Wildcat cartridge" based on the .284 Winchester) 30-284 Win.[7] 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[6] and very close to the 7.5×55mm Swiss.

In 2008, the most popular and useful .284 Winchester-case based cartridge was not the original, but rather the 6.5-284 Norma. 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.[8] 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. [9]

See also edit

References edit

  1. ^ a b ".284 Winchester data" from Accurate Powder 2006-07-18 at the Wayback Machine
  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) 2008-09-29 at the Wayback Machine
  4. ^ a b The .284 Winchester by Chuck Hawks
  5. ^
  6. ^ a b NOLASCO C.I.P. TDCC datasheet 30-284 NOLASCO
  7. ^ - 284 Win. C.I.P. TDCC datasheet 30 - 284 Win.
  8. ^ McPherson, M.L. . Rifle Shooter Magazine. Archived from the original on 2008-01-10. Retrieved 2008-01-13.
  9. ^ ".284 Winchester".

External links edit

  • .284 Winchester in 7mm Cartridge Guide by AccurateShooter.com
  • Obsolescent Rifle Cartridges by Chuck Hawks

January 01, 1970
winchester, 21x55mmrb, rebated, firearm, cartridge, introduced, winchester, 1963, center, with, left, remington, magnum, right, typerifleplace, originunited, statesproduction, historydesignerwinchesterdesigned1963manufacturerwinchesterproduced1963, presentspec. The 284 Winchester 7 21x55mmRB is a rebated rim firearm cartridge introduced by Winchester in 1963 284 Winchester 284 Winchester center with 308 Win left and 7mm Remington Magnum right TypeRiflePlace of originUnited StatesProduction historyDesignerWinchesterDesigned1963ManufacturerWinchesterProduced1963 presentSpecificationsCase typerebated rim bottleneckBullet diameter7 21 mm 0 284 in Land diameter7 00 mm 0 276 in Neck diameter8 13 mm 0 320 in Shoulder diameter12 06 mm 0 475 in Base diameter12 72 mm 0 501 in Rim diameter12 01 mm 0 473 in Rim thickness1 37 mm 0 054 in Case length55 12 mm 2 170 in Overall length71 12 mm 2 800 in Case capacity4 29 cm3 66 2 gr H2O Rifling twist254 mm 1 in 10 in Primer typeLarge rifleMaximum pressure C I P 440 00 MPa 63 817 psi Maximum pressure SAAMI 386 MPa 56 000 psi Ballistic performanceBullet mass type Velocity Energy100 gr 6 g HDY 100 HP 3 175 ft s 968 m s 2 238 ft lbf 3 034 J 120 gr 8 g SPR 120 SP 2 968 ft s 905 m s 2 347 ft lbf 3 182 J 139 gr 9 g HDY 139 SP 2 845 ft s 867 m s 2 498 ft lbf 3 387 J 150 gr 10 g Super X Power Point 2 860 ft s 870 m s 2 724 ft lbf 3 693 J Test barrel length 24 in 610 mm Source s Winchester Ammunition Accurate Powder 1 The 284 Winchester was designed to achieve 270 Winchester and 280 Remington performance from the new Winchester Model 100 autoloader and Winchester Model 88 lever action rifles The result was a 7 mm cartridge with about the same overall length as the 308 Winchester but with a wider body that yields a powder capacity about the same as that of the 270 Winchester and 280 Remington citation needed 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 2 Contents 1 History 2 Cartridge dimensions 3 Contemporary use 3 1 Wildcats 4 See also 5 References 6 External linksHistory editThe Savage Model 99 lever action Winchester Model 100 autoloader and Winchester Model 88 lever action rifles were available in 284 Winchester and Ruger produced a small run of Ruger M77 rifles in this caliber Ultra Light Arms still builds Model 20 rifles in 284 Winchester Cartridge dimensions editThe 284 Winchester has 4 29 ml 66 grains H2O of cartridge case capacity The case has a rebated rim and a body almost as large in diameter as that of typical belted magnum cases nbsp 284 Winchester maximum C I P cartridge dimensions All sizes in millimeters mm 3 Americans would 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 O lands 7 00 mm O grooves 7 19 mm land width 2 79 mm and the primer type is large rifle According to the official C I P guidelines the 284 Winchester case can handle up to 440 MPa 63 816 psi piezo pressure In C I P regulated countries every rifle cartridge combo has to be proofed at 125 of this maximum C I P pressure to certify for sale to consumers The SAAMI pressure limit for the 284 Winchester is set at 56 000 PSI 386 MPa 1 When the cartridge over all length is maintained deeper seating is necessary with long heavier bullets This reduces usable powder capacity and hence performance compared to longer action cartridges like the 280 Remington The American 280 Remington cartridge has probably the closest ballistics to the 284 Winchester The 280 Remington has a lower 405 MPa 58 740 psi C I P maximum allowed chamber pressure and slightly more case capacity Contemporary use editFor open country hunting of deer and pronghorn the 284 Winchester loaded with the Speer 130 grain 8 4 g spitzer at 3 100 ft s 940 m s is adequate even in a short action rifle Larger game calls for bullets weighing from 150 to 160 grains 10 g H4831 H450 H4350 H414 IMR 4350 and IMR 4831 are excellent powders 4 These ballistics show that the 284 Winchester is as good as the 280 Remington with the same weight bullet The short mountain rifles for which the 284 Winchester seems best suited seldom come with 24 inch barrels Aside from Winchester no other major company has ever loaded factory ammunition for the 284 Winchester 4 The cartridge is sometimes used for long range target shooting like F Class and 1 000 yd m long range competitions where participants usually handload their ammunition For this application the 284 Winchester is loaded with 175 and 180 gr very low drag bullets 5 The 284 Winchester is not popular in Europe where it competes with the 7 64mm to which it is almost ballistically identical When compared to the 284 Winchester the 7 64mm has a lower C I P maximum allowed chamber pressure and as a European 7 mm cartridge has a slightly larger bore European 7 mm cartridges all have 7 24 mm 0 285 in grooves O diameter American 7 mm cartridges have 7 21 mm 0 284 in grooves O Wildcats edit Main article Wildcat cartridge While it has been occasionally factory chambered in various rifles the chief reason for its survival has always been 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 6 and the extremely similar in the US considered a Wildcat cartridge based on the 284 Winchester 30 284 Win 7 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 6 and very close to the 7 5 55mm Swiss In 2008 the most popular and useful 284 Winchester case based cartridge was not the original but rather the 6 5 284 Norma 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 8 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 9 See also edit7mm 08 Remington 7 57mm Mauser 7 64mm 7 mm Remington Magnum List of rebated rim cartridges List of rifle cartridges Table of handgun and rifle cartridges Delta L problemReferences edit a b 284 Winchester data from Accurate Powder Archived 2006 07 18 at the Wayback Machine 7mm Accuracy Cartridges 284 Winchester at www accurateshooter com C I P decisions texts and tables free current C I P CD ROM version download ZIP and RAR format Archived 2008 09 29 at the Wayback Machine a b The 284 Winchester by Chuck Hawks What s Wrong With 30 Caliber By Bryan Litz a b NOLASCO C I P TDCC datasheet 30 284 NOLASCO 284 Win C I P TDCC datasheet 30 284 Win McPherson M L Wildcatting the 284 Winchester Long range shooters and wildcatters have kept the 284 alive Rifle Shooter Magazine Archived from the original on 2008 01 10 Retrieved 2008 01 13 284 Winchester External links edit 284 Winchester in 7mm Cartridge Guide by AccurateShooter com Obsolescent Rifle Cartridges by Chuck Hawks Retrieved from https en wikipedia org w index php title 284 Winchester amp oldid 1218816691, wikipedia, wiki, book, books, library,

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