During the time I was growing up, I don’t remember 6.5 mm cartridges being very popular with riflemen. The 6.5 Italian and 6.5 Arisaka were certainly soft-recoiling rifles that kids could shoot without sore shoulders and jaws afterward, but there wasn’t much interest in hunting big game with them.
The 6.5x55 Swedish Mauser was popular among a few hunters, but no one I knew hunted with one. Today, the 6.5x55 Swedish Mauser is getting a little more attention because of recoil sensitive shooters and the increased interest in 6.5-caliber cartridges.
Although 6.5 calibers have long been popular in Europe, American hunters showed little interest in them until the last few years.
In 2002, Alexander Arms invented the 6.5 Grendel for its AR-15 rifles. The 6.5 Grendel case looks pretty much like a 7.62x39 Soviet case. The Alexander Arms website admits that, “The origins of the 6.5 Grendel may be traced back to the Soviet 7.62x39.” The 6.5 Grendel is a flat-shooting cartridge that seems to handle varmints as well as deer-sized big game. Recoil is listed as 8.9 foot-pounds with a 120-grain bullet, out of a 7.5 pound rifle, recoiling back at the shooter at 8.8 feet per second.
The introduction of the 6.5 Grendel with its high-ballistic coefficient, 120-grain bullet traveling at 2,600 feet per second and flat trajectory got the attention of a lot of American shooters after a few gun magazines started singing its praises as a varmint and deer rifle.
Most of the successful 6.5-caliber cartridges that have been develop in the last few year have two distinguishing features they generally use long bullets and work best with a one in eight inch twist barrel.
In the last 10 years, more 6.5 cartridges have been developed and are being used for game as big as elk as well as deer. Hornady developed the 6.5 Creedmoor as a target rifle, and it quickly became an overnight sensation because of its 3,020-feet-per second muzzle velocity and its long bullet’s ballistic coefficient of almost .600, which retains enough energy to take deer, elk, and moose at long range if necessary.
The 6.5 Creedmoor with a 140-grain bullet recoils at about 12 foot-pounds of energy, recoiling at the shooter at 10 feet per second, making it ideal for young hunters and others that are recoil sensitive.
Two trends I see in some of the newer 6.5-caliber offerings — and I’m not sure I like — are the tendency to develop cartridges that have pretty much the same ballistic characteristics, and cases that have more powder and pressures than the smaller bore can efficiently handle, which can damage the under-bored 6.5-caliber chambers and barrels over time.
Recently, Weatherby introduced the 6.5 Weatherby RPM (Rebated Precision Magnum). It is very new and we don’t know as much as we would like to know about the RPM, but preliminary information states that it fills the gap between the .30-06 Springfield and the .300 Winchester Magnum. If you know your cartridges and are wondering, “Doesn’t the .264 Winchester do that?” The answer is yes, but the .264 uses a 140-grain bullet at 3,200 feet per second, while the Weatherby 6.5 RPM shoots two bullet weights at three different velocities: 127 grain at 3,225 feet per second muzzle velocity, 140-grain Norma bullet at 2,975 feet per second muzzle velocity and a 140-grain Nosler bullet at 3,075 feet per second muzzle velocity. Still, the ballistics of the .264 and the new Weatherby 6.5 RPM would seem to be almost identical, and a rifleman that loads his own ammunition could reload any weight 6.5 bullet the Weatherby RPM currently uses.
Weatherby also offers a 6.5-300 Weatherby Magnum in their lineup of Weatherby calibers for big game. The .300 Weatherby magnum case is simply necked down to accept a 6.5mm bullet. Initial loads include a 127 LRX bullet at 3,531 feet per second muzzle velocity, a Swift 130-grain Scirocco at 3,476 feet per second muzzle velocity and a 140-grain A-Frame bullet at 3,395 feet per second muzzle velocity.
The Sporting Arms and Ammunition Manufacturer’s Institute recommends a maximum of 65,000 pounds per square inch barrel pressure for 6.5 calibers. The Weatherby 6.5-300 Weatherby Magnum achieves all of that.
My concern is that the pressure generated by the 6.5 Weatherby Magnum will cause a lot of wear and tear on the barrel with repeated use, which should eventually affect accuracy.
I have always wondered why manufacturers don’t put the barrels of firearms that will be subjected to abnormally high pressures through the ferritic nitocarburization process or what is simply referred to as nitriding, This process makes the inside of the chamber and barrel, as well as the outer surface of the barrel, much harder and more resistant to eroding with out changing the caliber because nitriding isn’t a lining. It is a process that makes the metal harder by becoming part of the barrel s metal composition leaving the lands and grooves sharp while improving accuracy.
Several manufacturers of AR-16 rifles are including nitrided barrels with their rifles, rather than chrome lined barrels because they seem to be more durable and accurate.
Right now the most popular 6.5mm calibers seem to be in no particular order, the 6.5x55 mm Swedish Mauser, the 6.5 mm Grendel, the 6.5 mm Creedmoor and the .264 Winchester Magnum.
Smokey Merkley was raised in Idaho and has been hunting since he was 10 years old. He can be contacted at mokeydo41245@hotmail.com.
