Feral Jundi

   In this post, I wanted to present two types of rounds being thrown around out there as possible replacements for the 5.56 mm round currently in use by today’s warfighters.  Wikipedia is the source for both of these reviews, and is certainly a good foundation for us to start from.  And like Col. John Boyd would ask, is this the bullet that we want, and is this the rifle that we want to shoot it with?

     Are we on the right track, by trying to fit a new round into an old rifle system like the M-4?  Should we be designing a weapon around the bullet, or the bullet around the weapon?  I like the ergonomics of the M-4, but is this a good idea to limit ourselves on the bullet, just because we want to save money on weapon design?  Or perhaps we should just start from scratch, and go with the best rifle that is designed around the best bullet for the job.  My personal opinion is to throw out doctrine and build that ‘snowmobile’, to get that round and rifle that we want.

    And if you talk with others out there about what guys want, they want a hard hitting and accurate round.  They want something that is going to put that bad guy down with one shot or rip a limb off when it hits them.  They want something that will be hard hitting beyond the 300 meter point, as well as accurate at all the pertinent ranges.  They also want a rifle that is ergonomic, lightweight, requires little maintenance, is easy to clean and fix, is tough, and will last awhile.  They want a rifle that can operate in all conditions and will work when they need it most.  A tall order, but not impossible to come up with.

    But if I had to choose between the rounds being evaluated right now, my personal opinion is that I like the 6.5 Grendel.  I want an accurate round that can hit hard at all ranges, and not just up to the 300 meter ranges.  Where as both rounds are sufficient, the 6.5 sounds like a better designed bullet for this.

    The other thing to remember is that both rounds were ham-stringed by the fact that they both had to be the same length as the 5.56mm.  The reason is cost.  Both of these rounds could be fed into an M-4 type platform with moderate modification to the original weapon.  But like I said, what would Boyd say?  Are we putting a ‘pretty bow’ on a shitty round, or are you getting the bullet that we want?  And are we getting the rifle that we want, that can shoot this round?  Things to ponder, as the war continues.  –Head Jundi

 

 

6.8 mm Remington SPC (Left) as compared to the 5.56x45mm NATO cartridge (Right)

 

6.8 mm Remington SPC

From Wikipedia, the free encyclopedia

Type Rifle

Place of origin Flag of the United States United States

Production history

Designer Remington, SOCOM

Designed 2002-2004

Specifications

Parent case .30 Remington

Case type Rimless, bottlenecked

Bullet diameter 0.277 in (7.0 mm)

Neck diameter 0.298 in (7.6 mm)

Shoulder diameter 0.402 in (10.2 mm)

Base diameter 0.421 in (10.7 mm)

Rim diameter 0.422 in (10.7 mm)

Rim thickness 0.049 in (1.2 mm)

Case length 1.676 in (42.6 mm)

Overall length 2.315 in (58.8 mm)

Ballistic performance

Bullet weight/type Velocity Energy

115 gr (7.5 g) (7.45g) 2,625 ft/s (800 m/s) 1,759 ft·lbf (2,385 J)

Test barrel length: 24 in (609.6 mm)

Source: Remington [1]

The 6.8 mm Remington SPC (or 6.8x43mm) is a new rifle cartridge that was developed with collaboration from individual members of US SOCOM.[2] Based upon the .30 Remington cartridge [3], it is midway between the 5.56x45mm NATO and 7.62x39mm in bore diameter and velocity with more energy than both. It is particularly adaptable to current 5.56 mm NATO firearms, the cartridge overall length being comparable.

Though ballistically similar to the 1950s-era .280 British, improved propellant powders allow the 6.8 mm a smaller case. The 6.8 mm SPC (Special Purpose Cartridge) has a muzzle velocity in the 2,400 feet per second (730 m/s) range from a 16 inch (406 mm) barrel using a 115-grain bullet.

Contents

    * 1 Performance

          o 1.1 Muzzle velocity from a 24-inch (610 mm) barrel

    * 2 See also

    * 3 Notes

    * 4 External links

Performance

The 6.8 mm Remington SPC is designed to deliver 44% greater energy than the 5.56 mm NATO at 100-200 meters.[4] When compared to the more powerful and well-established 7.62x51mm NATO cartridge, the 6.8 mm falls short in all of these areas, but has less recoil and is more controllable. While the 6.8 mm generates around 1,759 ft·lbf (2385 J) of muzzle energy with its 115 grain bullet (note: this figure is from a 24″ bolt-action test barrel, not the 14.5 inch barrel of the M4 Carbine), the 7.62 mm NATO (M80) fires a 147 grain bullet at 2,750 ft/s for 2460 ft·lbf of energy (838.2 m/s for 3335 J).

While the round is generally intended for use at shorter ranges, this handicap somewhat dampened the initial enthusiasm over the SPC round, and given competitors like the 6.5 Grendel or improved 5.56 mm rounds an opportunity to compete for acceptance. Many criticisms fall short considering the majority of military engagements (even with modern optics) occur inside 300 m (U.S. Army Continental Army Command Operations Research Office ALCLAD study, and Gen. S.L.A Marshall, cited on p. 15, “The Complete AR-15/M-16 Sourcebook”, Duncan Long, Paladin Press 1992, 2007)

The first major manufacturer to offer a 6.8 mm Remington SPC chambered version of the AR-15 was Barrett Firearms Company, offering the Barrett M468. By 2007, most major manufacturers of AR-15 type rifles for the civilian gun market, such as Bushmaster Firearms International, DPMS Panther Arms and Rock River Arms were also producing 6.8 mm Rem SPC carbines. Ruger Firearms produces a 6.8 mm version of their popular Ruger Mini-14 series carbine [5].

Muzzle velocity from a 24-inch (610 mm) barrel

    * 7.45 g (115 gr) Full Metal Jacket (FMJ): 2,625 ft/s (800.1 m/s)

    * 7.45 g (115 gr) Boat Tail Hollow Point (BTHP): 2,624 ft/s (799.8 m/s)

    * 7.45 g (115 gr) Sierra Match King (SMK): 2,625 ft/s (800.1 m/s)

———————

7.62 mm NATO, 6.5 Grendel, 5.56 mm NATO

6.5 mm Grendel

From Wikipedia, the free encyclopedia

Place of origin Flag of the United States United States

Production history

Designer Bill Alexander

Designed 2003 [1]

Specifications

Parent case PPC

Case type Rimless, bottleneck

Bullet diameter 6.5 mm (0.26 in)

Neck diameter 7.44 mm (0.293 in)

Shoulder diameter 10.87 mm (0.428 in)

Base diameter 11.15 mm (0.439 in)

Rim diameter 11.2 mm (0.44 in)

Rim thickness 1.5 mm (0.059 in)

Case length 38.7 mm (1.52 in)

Overall length 57.5 mm (2.26 in)

Rifling twist 1 in 8″ or 1 in 9″

Primer type Small rifle

Ballistic performance

Bullet weight/type Velocity Energy

90 gr (5.8 g) Speer TNT 2,880 ft/s (880 m/s) 1,658 ft·lbf (2,248 J)

120 gr (7.8 g) Norma FMJBT 2,700 ft/s (820 m/s) 1,942 ft·lbf (2,633 J)

123 gr (8.0 g) Sierra Matchking 2,650 ft/s (810 m/s) 1,917 ft·lbf (2,599 J)

130 gr (8.4 g) Norma 2,510 ft/s (770 m/s) 1,818 ft·lbf (2,465 J)

108 gr (7.0 g) Scenar (moly) 2,790 ft/s (850 m/s) 1,866 ft·lbf (2,530 J)

Test barrel length: 24 inches

Source: Alexander Arms Pressure-safe Load Data

20″ Grendel Counter-Sniper

20″ Grendel Counter-Sniper

The 6.5 mm Grendel (or 6.5x39mm Grendel) is a 6.5 mm caliber intermediate cartridge developed in 2002 by Bill Alexander of Alexander Arms and Arne Brennan of Competition Shooting Sports. This cartridge is an evolution of Dr. Lou Palmisano’s PPC case which has dominated competition shooting for over 20 years.[1] The 6.5 Grendel was designed as a low recoil, high accuracy, long-range cartridge for the AR-15 platform.

Contents

    * 1 Development and history

          o 1.1 Timeline

    * 2 Performance

          o 2.1 External ballistics

          o 2.2 Terminal ballistics

    * 3 Notes

    * 4 Periodical References (with no online copy)

    * 5 See also

    * 6 External links

Development and history

The Grendel design philosophy was “start slow and end fast”. High muzzle velocities accelerate barrel wear and increase the percentage of recoil due to escaping gases but only yield good impact energy if the bullet is efficient at carrying its velocity downrange. Constrained by the length of the 5.56 mm NATO round, but wanting to launch a much heavier bullet, the Grendel designers hit on a short, fat case for more powder volume while saving space for long, streamlined, high ballistic coefficient (BC) bullets that give up little of their energy in-flight. Firing factory bullets from 90 to 129 grains (5.8–8.4 g), its muzzle velocity ranges from 2,500 ft/s (760 m/s) with 129- and 130-grain (8.4 g) bullets to 2,900 ft/s (880 m/s) with 90 gr (5.8 g) bullets (similar in velocity to a 5.56 mm 77-grain (5.0 g) round).

Timeline

    * 1998: Arne Brennan investigates .22 PPC, 6 PPC in search of a more capable competition and hunting round.

    * 2000: Arne Brennan begins shooting a 6.5 PPC wildcat cartridge from his custom AR-15 platform.

    * 2001: Arne Brennan and Bill Alexander introduced to each other by Lothar Walther.

    * Mar 2002: First production 6.5 Grendel brass cartridges manufactured to specification by Lapua.

    * May 2003: First prototype 6.5 Grendel weapon demonstrated at Blackwater Shoot-out.

    * May 2006: Independent ballistic gelatin testing completed for 90 gr (5.8 g) TNT, 120 grains (7.8 g) Norma, 120 gr (7.8 g) SMK, and 123 grains (8.0 g) SMK prototype.

    * Aug 2006: Bill Alexander publishes pressure safe load table for AR platforms with 14.5- to 28.0-inch (370–710 mm) barrels.

    * Feb 2007: Production Wolf brand ammunition becomes available.

Performance

Proponents assert that the Grendel is an ideal middle ground between the 5.56 mm NATO and the 7.62 mm NATO, taking the best attributes of each. It has a flatter trajectory and retains greater terminal energy at extended ranges than either of these cartridges due to its higher ballistic coefficient.[2] Production rifles have consistently achieved sub–minute of arc (MOA) groups at test ranges out past 600 meters.[3] On March 6, 2006, Arne Brennan achieved a witnessed 1.198 inches (30.4 mm) group at 660 yards (600 m).[4] Similar accuracy was demonstrated at recent Blackwater Shootouts.[5] Competitions have begun to be won with the 6.5 Grendel although use of the round is still not common in competition.

As noted above, the Grendel case is very closely related to the PPC case. When sufficient load data was made available, a thorough study of the Grendel case, which constitutes a precisely dimensioned combustion chamber when the round is chambered, was done with the following results. In general, each additional grain of bullet weight will reduce muzzle velocity by 10 ft/s (3 m/s) and each additional inch of barrel length will increase muzzle velocity by 20 ft/s (6 m/s). Therefore, a handy rule of thumb is “one inch of barrel length equals two grains of bullet weight (1 mm ? 5 mg)”. Specific details are available as graphs derived from Alexander Arms’ public domain load table linked below.

Alexander Arms contracted Speer Law Enforcement to perform terminal ballistics tests in accordance with standard F.B.I. Protocols and their standard in-house procedures. They use 6 in × 6 in × 16 in (150 mm × 150 mm × 400 mm) blocks of ten percent ballistic gelatin, calibrated with a BB. These results were made public in May 2006. All tests were completed using either 14.5- or 16.0-inch (370 or 400 mm) chrome-lined Alexander Arms Tactical rifles and shot from either 50 or 100 yards (45 or 90 m) to simulate combat conditions using short-barreled M4 format weapons. Barrel pressures were less than 345 MPa (50,000 psi). These are all production rifles and ammunition except for the prototype 123 gr (8.0 g) Sierra MatchKing (now a production bullet). In addition to the photos shown below, a 90 gr (5.8 g) TNT was tested resulting in explosive fragmentation after penetrating only 0.5 in (13 mm).

The 120-grain (7.8 g) Sierra MatchKing penetrated 3.25 inches (83 mm) before yawing and fragmenting. The Alexander Arms Tactical 16 carbine (16 in/410 mm barrel) was used at a range of 100 yards (91 m). Impact velocity: 2,383 feet per second (726 m/s). Maximum penetration of the 120 gr (7.8 g) SMK was 19.5 inches (500 mm), maximum permanent cavity diameter was more than 6 inches (150 mm) with lesions running to gel block exterior surfaces. Depth to the maximum permanent cavity was 7.5 inches (190 mm). The bullet fragmented, with seven large pieces visible within the block. Jacket sections came to rest at 11.75 and 16.25 inches (298 mm and 413 mm), and the bullet core at 19.5 inches (500 mm).

The prototype 123 gr (8.0 g) SMK penetrated 2 inches (51 mm) before yawing and fragmenting. The Alexander Arms Tactical 14.5 carbine (14.5 inches (370 mm) barrel) was used at a range of 50 yards (46 m). Impact velocity was 2,385 ft/s (727 m/s). The 123 SMK penetrated to a depth of 16.2 inches (410 mm), maximum permanent cavity diameter was more than 6 inches (150 mm) with lesions running to block exterior surfaces. Depth to the maximum permanent cavity was 7 inches (180 mm). The bullet fragmented into multiple small fragments with jacket pieces visible at 11 and 13 inches (280 and 330 mm). A small core fragment was visible at a maximum depth of 16.2 inches (410 mm).

The 120 gr (7.8 g) Norma FMJ penetrated 16.5 inches (420 mm) before veering out the side of the block and impacting the support frame. No fragmentation was evident, but the slug is believed to have tumbled at about 7 inches (180 mm) with its maximum permanent cavity at 11 inches (280 mm). Lesions of more than 6 inches (150 mm) were torn through the top and bottom block surfaces. The bullet was fired from an Alexander Arms Tactical 14.5-inch (370 mm) AR-15 rifle at a range of 50 yards (46 m) with a chronographed impact velocity of 2,405 ft/s (733 m/s).