Difference between revisions of ".277 Wolverine"

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One major difference between the .277 Wolverine and cartridges such as the [[6.5 Grendel]] or [[6.8 SPC]], is that the Wolverine is ''directly'' based on the 5.56 cartridge and is merely necked up to accept a larger caliber bullet. This is the same design philosophy used on rounds like the [[.300 Whisper]] and [[.300 Blackout]]. As a result, the round can feed from a standard AR-15 / [[STANAG magazine]]. It also means that magazine capacity is ''not'' hindered in any way.
 
One major difference between the .277 Wolverine and cartridges such as the [[6.5 Grendel]] or [[6.8 SPC]], is that the Wolverine is ''directly'' based on the 5.56 cartridge and is merely necked up to accept a larger caliber bullet. This is the same design philosophy used on rounds like the [[.300 Whisper]] and [[.300 Blackout]]. As a result, the round can feed from a standard AR-15 / [[STANAG magazine]]. It also means that magazine capacity is ''not'' hindered in any way.
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== Design ==
 
== Design ==
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The .277 Wolverine was developed by [[Mark Kexel]] of [[Mad Dog Weapon Systems]] in 2014.
  
 
For similar reasons that a .277 inch (7.04 mm) diameter bullet was selected for the [[6.8 SPC]] (ideal mass-to-diameter-to-length for mid-weight bullets constrained to loading in an AR-15/M16 [[STANAG magazine]]), 6.8mm became the caliber for this new AR-15 wildcat cartridge. Like the .300 AAC Blackout and unlike the 6.8 SPC and other "larger bore" AR-15 cartridges, the .277 Wolverine is based on the widely available 5.56×45mm parent case. Therefore, rifle components such as the bolt and magazine are fully interchangeable between 5.56×45mm and .277 Wolverine firearms, and AR-15 magazines can be used with zero loss in capacity. Overall, a new barrel is the main component needed to be changed in order to convert a standard AR-15 to .277 Wolverine.
 
For similar reasons that a .277 inch (7.04 mm) diameter bullet was selected for the [[6.8 SPC]] (ideal mass-to-diameter-to-length for mid-weight bullets constrained to loading in an AR-15/M16 [[STANAG magazine]]), 6.8mm became the caliber for this new AR-15 wildcat cartridge. Like the .300 AAC Blackout and unlike the 6.8 SPC and other "larger bore" AR-15 cartridges, the .277 Wolverine is based on the widely available 5.56×45mm parent case. Therefore, rifle components such as the bolt and magazine are fully interchangeable between 5.56×45mm and .277 Wolverine firearms, and AR-15 magazines can be used with zero loss in capacity. Overall, a new barrel is the main component needed to be changed in order to convert a standard AR-15 to .277 Wolverine.
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The initial design focused on optimal performance with supersonic bullets in the 85-115 gr (5.5-7.5 g)  weight class. As a result, a 1:11 twist rate barrel with [[5R Rifling]] was initially selected. Subsequent consumer interest in firing "heavy-for-caliber" subsonic bullets led to the design, testing, and production of 1:7 twist barrels in order to stabilize the longer and heavier projectiles.
 
The initial design focused on optimal performance with supersonic bullets in the 85-115 gr (5.5-7.5 g)  weight class. As a result, a 1:11 twist rate barrel with [[5R Rifling]] was initially selected. Subsequent consumer interest in firing "heavy-for-caliber" subsonic bullets led to the design, testing, and production of 1:7 twist barrels in order to stabilize the longer and heavier projectiles.
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== Development ==
 
== Development ==
  
  
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== Specifications ==
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* '''Parent case:''' [[5.56 NATO]]
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* '''Case type:''' Rimless, Bottleneck
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* '''Bullet diameter:''' 0.277 in (7.04 mm)
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* '''Neck diameter:''' 0.3089 in (7.85 mm)
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* '''Shoulder diameter:''' 0.356 in (9.04 mm)
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* '''Base diameter:''' 0.377 in (9.58 mm)
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* '''Rim diameter:''' 0.378 in (9.60 mm)
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* '''Case length:''' 1.530 - 1.535 in (38.86 mm, trim) to 1.545 in (39.24 mm, max.)
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* ''Overall length:''' 2.26 in (57.40 mm) max. COAL (typical)
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* '''Rifling twist:''' 1:7 (subsonic/supersonic), 1:11 (supersonic)
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* '''Primer type:''' Small rifle
  
  
 
== Ballistic Performance ==  
 
== Ballistic Performance ==  
  
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{| class="wikitable"
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|-
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! Bullet Weight / Type !! Velocity !! Muzzle Energy
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|-
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|85 gr (6 g) || 2,800 ft/s (850 m/s) || 1,480 ft lbf (2,010 J)
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|-
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|90 gr (6 g) || 2,750 ft/s (840 m/s) || 1,510 ft lbf (2,050 J)
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|-
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|95 gr (6 g) || 2,650 ft/s (810 m/s) || 1,480 ft lbf (2,010 J)
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|-
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|100 gr (6 g) || 2,600 ft/s (790 m/s) || 1,500 ft lbf (2,000 J)
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|-
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|110 gr (7 g) || 2,500 ft/s (760 m/s) || 1,525 ft lbf (2,068 J)
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|}
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=== Ballistic Performance Compared to Other Cartridges ===
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{| class="wikitable"
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|-
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! Round !! Bullet Weight !! Barrel Length !! Muzzle Velocity !! Ballistic Coefficient (G1) !! Energy at 300 Yards
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|-
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|5.56×45mm (M855) || 62 gr (4.0 g) || 16 in (410 mm) || 2,900 ft/s (880 m/s) || 0.304 || 579 ft lbf (785 J)
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|-
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|7.62×39mm || 123 gr (8.0 g) || 16.5 in (420 mm) || 2,300 ft/s (700 m/s) || 0.300 || 633 ft lbf (858 J)
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|-
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|300 BLK || 110 gr (7.1 g) || 16 in (410 mm) || 2,300 ft/s (700 m/s) ||0.300 ||622 ft⋅lbf (843 J)
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|-
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|300 BLK || 125 gr (8.1 g) || 16 in (410 mm) || 2,200 ft/s (670 m/s) || 0.320 || 644 ft⋅lbf (873 J)
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|-
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|.277 Wolverine || 90 gr (5.8 g) || 16 in (410 mm) || 2,750 ft/s (840 m/s) || 0.275 || 736 ft⋅lbf (998 J)
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|-
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|.277 Wolverine || 100 gr (6.5 g) || 16 in (410 mm) || 2,600 ft/s (790 m/s) || 0.323 || 754 ft⋅lbf (1,022 J)
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|-
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|.277 Wolverine || 110 gr (7.1 g) || 16 in (410 mm) || 2,500 ft/s (760 m/s) || 0.370 || 837 ft⋅lbf (1,135 J)
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|}
  
  

Revision as of 07:49, 20 March 2021

A picture showing a comparison between various cartridges, such as the .277 Wolverine, 6.8 SPC and 5.56 NATO.

The .277 Wolverine (6.8×39mm) is a wildcat cartridge based on the 5.56x45mm NATO round and was designed by Mark Kexel of Mad Dog Weapon Systems in 2014. It is a versatile mid-powered cartridge with better ballistic performance over the AR-15's traditional .223 Remington / 5.56×45mm NATO chamberings. Converting from .223 / 5.56 to the .277 Wolverine requires only a new barrel. It utilizes small rifle primers, as well as .277 caliber projectiles (like the similar 6.8 SPC, the .270 Winchester, as well as the highly anticipated .27 Nosler and .277 Fury).

One major difference between the .277 Wolverine and cartridges such as the 6.5 Grendel or 6.8 SPC, is that the Wolverine is directly based on the 5.56 cartridge and is merely necked up to accept a larger caliber bullet. This is the same design philosophy used on rounds like the .300 Whisper and .300 Blackout. As a result, the round can feed from a standard AR-15 / STANAG magazine. It also means that magazine capacity is not hindered in any way.


Design

The .277 Wolverine was developed by Mark Kexel of Mad Dog Weapon Systems in 2014.

For similar reasons that a .277 inch (7.04 mm) diameter bullet was selected for the 6.8 SPC (ideal mass-to-diameter-to-length for mid-weight bullets constrained to loading in an AR-15/M16 STANAG magazine), 6.8mm became the caliber for this new AR-15 wildcat cartridge. Like the .300 AAC Blackout and unlike the 6.8 SPC and other "larger bore" AR-15 cartridges, the .277 Wolverine is based on the widely available 5.56×45mm parent case. Therefore, rifle components such as the bolt and magazine are fully interchangeable between 5.56×45mm and .277 Wolverine firearms, and AR-15 magazines can be used with zero loss in capacity. Overall, a new barrel is the main component needed to be changed in order to convert a standard AR-15 to .277 Wolverine.

To load heavier (longer) bullets to magazine length without problems seating the bullet's ogive into the case mouth, the Wolverine case is shortened to approximately 39 mm from its 45 mm parent brass. The case is resized and formed in a single operation to create a new 23-degree shoulder and a larger neck.

The initial design focused on optimal performance with supersonic bullets in the 85-115 gr (5.5-7.5 g) weight class. As a result, a 1:11 twist rate barrel with 5R Rifling was initially selected. Subsequent consumer interest in firing "heavy-for-caliber" subsonic bullets led to the design, testing, and production of 1:7 twist barrels in order to stabilize the longer and heavier projectiles.



Development

Specifications

  • Parent case: 5.56 NATO
  • Case type: Rimless, Bottleneck
  • Bullet diameter: 0.277 in (7.04 mm)
  • Neck diameter: 0.3089 in (7.85 mm)
  • Shoulder diameter: 0.356 in (9.04 mm)
  • Base diameter: 0.377 in (9.58 mm)
  • Rim diameter: 0.378 in (9.60 mm)
  • Case length: 1.530 - 1.535 in (38.86 mm, trim) to 1.545 in (39.24 mm, max.)
  • Overall length:' 2.26 in (57.40 mm) max. COAL (typical)
  • Rifling twist: 1:7 (subsonic/supersonic), 1:11 (supersonic)
  • Primer type: Small rifle


Ballistic Performance

Bullet Weight / Type Velocity Muzzle Energy
85 gr (6 g) 2,800 ft/s (850 m/s) 1,480 ft lbf (2,010 J)
90 gr (6 g) 2,750 ft/s (840 m/s) 1,510 ft lbf (2,050 J)
95 gr (6 g) 2,650 ft/s (810 m/s) 1,480 ft lbf (2,010 J)
100 gr (6 g) 2,600 ft/s (790 m/s) 1,500 ft lbf (2,000 J)
110 gr (7 g) 2,500 ft/s (760 m/s) 1,525 ft lbf (2,068 J)

Ballistic Performance Compared to Other Cartridges

Round Bullet Weight Barrel Length Muzzle Velocity Ballistic Coefficient (G1) Energy at 300 Yards
5.56×45mm (M855) 62 gr (4.0 g) 16 in (410 mm) 2,900 ft/s (880 m/s) 0.304 579 ft lbf (785 J)
7.62×39mm 123 gr (8.0 g) 16.5 in (420 mm) 2,300 ft/s (700 m/s) 0.300 633 ft lbf (858 J)
300 BLK 110 gr (7.1 g) 16 in (410 mm) 2,300 ft/s (700 m/s) 0.300 622 ft⋅lbf (843 J)
300 BLK 125 gr (8.1 g) 16 in (410 mm) 2,200 ft/s (670 m/s) 0.320 644 ft⋅lbf (873 J)
.277 Wolverine 90 gr (5.8 g) 16 in (410 mm) 2,750 ft/s (840 m/s) 0.275 736 ft⋅lbf (998 J)
.277 Wolverine 100 gr (6.5 g) 16 in (410 mm) 2,600 ft/s (790 m/s) 0.323 754 ft⋅lbf (1,022 J)
.277 Wolverine 110 gr (7.1 g) 16 in (410 mm) 2,500 ft/s (760 m/s) 0.370 837 ft⋅lbf (1,135 J)


Applications

Comparisons