6.5mm Grendel

The 6.5mm Grendel design goal was to create an effective 200–800 yard STANAG magazine-length cartridge for the AR-15 that surpassed the performance of the native 5.56mm NATO/.223 Remington cartridge. Constrained by the dimension of the magazines, the Grendel designers decided to use a shorter, larger diameter case for higher powder volume while allowing space for long, streamlined, high-ballistic coefficient (BC) bullets. Firing factory-loaded ammunition with bullets ranging from 90 to 129 grains (5.8 to 8.4 g), its muzzle velocity varies 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). Depending on their case material and bullet, 6.5 Grendel cartridges weigh 14.7 to 17.8 grams (227 to 275 gr).

The case head diameter of the Grendel is the same as that of the .220 Russian, 7.62×39mm and 6.5mm PPC cases. This diameter is larger than the 5.56×45mm NATO, thereby necessitating the use of a non-standard AR-15 bolt. The increased case diameter results in a small reduction in the capacity of standard size M16/AR-15 magazines. A Grendel magazine with the same dimensions as a 30-round STANAG magazine will hold 26 rounds of 6.5mm Grendel ammunition.

C-Products 26-round Grendel Magazine

Proponents assert that the Grendel is a middle ground between the 5.56×45mm NATO and the 7.62×51mm NATO. It retains greater terminal energy at extended ranges than either of these cartridges due to its higher ballistic coefficient.[2] For example, the 123 gr (8.0 g) 6.5 Grendel has more energy and better armor penetration at 1,000 meters than the larger and heavier 147 gr (9.5 g) M80 7.62 NATO round.[8][9][10][11]

In order to obtain ballistics that are superior to the 7.62×51mm cartridge, a weapon with a longer barrel and firing a heavier bullet is necessary. To achieve the same results from shorter length barrels, even heavier bullets are needed.[12]

External ballistics

Muzzle Velocity Change with Bullet Weight

Bullet velocity: 24 inch (609.6 mm) barrel
	Bullet mass		Muzzle velocity		1,000 meter velocity
	gr	g	ft/s	m/s	ft/s	m/s
Lapua Scenar	108	7.0	2,700	820	1,166	355
Lapua Scenar	123	8.0	2,620	800	1,222	372
Lapua FMJBT	144	9.3	2,450	750	1,213	370

As noted above, the Grendel case is very closely related to the .220 Russian case. In general, each additional grain of bullet weight will reduce muzzle velocity by 10.8 ft/s (6.1 m/s for each gram) and each additional inch of barrel length will increase muzzle velocity by 20 ft/s (2.4 m/s for each centimeter). Specific details are available as graphs derived from Alexander Arms' public domain load table linked below.

Serbia is in process of adopting a rifle made by Zastava Arms [13] in 6.5 mm Grendel caliber as main armament for its armed forces. The rifle, designated M17, is a derivative of the previous-issue M70 rifle.[14] An American-manufactured rifle in 6.5mm Grendel caliber may also be adopted in armament for special forces units after it passes testing in Technical Testing Center. Three types of 6.5mm Grendel ammunition produced by Prvi Partizan Užice Serbia will be tested for use with these rifles.[15][16][17][18][19]

• .220 Russian (5.6×39 mm)
• .224 Valkyrie (5.6×41 mm)
• 6.8mm Remington SPC
• 6.5mm Creedmoor
• .30 Walker
• 6mm PPC
• 6mm AR: a 6.0mm version which shares Grendel's casing, but sends a (usually) lighter projectile up to 1,000 yards (900 m).
• 7.62x39mm
• List of AR platform calibers
• List of rifle cartridges
• Table of handgun and rifle cartridges
• 6.5×42mm, also known as 6.5 MPC (Multi Purpose Cartridge), based on a necked up .223 Remington case.[20]

Wikimedia Commons has media related to 6.5mm Grendel.

• http://www.alexanderarms.com/