The 6.8mm Remington SPC
By Chuck Hawks
The inadequacies of the 5.56mm NATO as a service rifle cartridge are well documented and have inspired many suggestions regarding possible replacements (some on this web site). Soldiers in the U.S. Special Operations Command also realized the need for a more potent round and initiated (on their own recognizance) development of a new cartridge designed to work in the M16 action.
The new .270 caliber (6.8mm) cartridge is the result of at least a two year cooperative effort between individuals in the 5th Special Forces Group, the Army Marksmanship Unit, and Remington. The old .30 Remington was eventually chosen as the basic case from which the new cartridge would spring, as its rim size required only minimal modification to the M16's bolt face. Following typical modern procedure, the .30 Rem. case was shortened (to a length of 43mm), blown out, necked-down, and given a sharper shoulder and a shorter neck. The resulting cartridge will function properly in an M16 length action and magazine.
Various calibers from .22 to .30 were tested before settling on a standard .277" diameter bullet, the same bullet diameter made famous in the .270 Winchester. A new powder has reportedly been developed to optimize the ballistics of the new cartridge.
Unfortunately, also typical of modern practice, a light bullet of relatively poor sectional density (SD) was chosen, in this case weighing 115 grains. This means a SD of only .214, robbing the .270 caliber of perhaps its biggest advantage as a hunting cartridge.
The ballistic coefficient (BC) of the new Remington 115 grain match bullets is .340, and the BC of their metal case bullet is .325. For comparison, the Winchester Ballistic Silvertip 130 grain .270 hunting bullet has a SD of .242 and a BC of .433.
The intrinsic accuracy of the new military cartridge is alleged to be exceptional, capable of shooting 1 MOA groups out to very long range (in excess of 600 yards!). Its trajectory is comparable to the 7.62mm NATO (.308 Winchester) cartridge. The military nomenclature for the new cartridge is 6.8x43mm SPC, and Remington is introducing it to civilian shooters in 2004 as the 6.8mm Remington SPC.
Remington is offering four 6.8mm factory loads, all with 115 grain bullets. These will include two target loads, a Core-Lokt Ultra hunting load, and a Metal Case military-type load. The four factory loads all have a muzzle velocity (MV) of 2800 fps and a muzzle energy (ME) of 2002 ft. lbs. from a 24" test barrel. At 100 yards the metal case bullet (BC .325) has a remaining velocity of 2523 fps and energy of 1625 ft. lbs. At 200 yards the velocity is 2262 fps and the energy 1307 ft. lbs. And at 300 yards the velocity is 2017 fps and the remaining energy 1039 ft. lbs. These figures are taken from Remington's 2004 catalog.
The trajectory of the metal case bullet looks like this: +1.2" at 50 yards, +2.7" at 100 yards, + 2.8" at 150 yards, +1.4" at 200 yards, -3" at 267 yards, and -6.6" at 300 yards. The maximum point blank range (+/- 3") is thus 267 yards. These figures are computed for a rifle with a telescopic sight mounted 1.5" over the bore. This, just like the Army claimed, is similar to the trajectory of the .308 with a 150 grain bullet.
In terms of killing power as a hunting cartridge, the Optimum Game Weight formula shows that the new 6.8mm SPC should be optimal for 200 pound game out to about 245 yards. It would seem that its killing power is nicely matched with its trajectory, one indication of a well balanced cartridge.
Some writers in the popular shooting press have predicted that the 6.8mm SPC is going to be a great new long range (out to at least 300 yards) medium game cartridge, but this is clearly an exaggeration. Remington, after all, is a big advertiser. As one might logically expect, the killing power the new cartridge is similar to its .30 Remington parent cartridge, which was itself a rimless version of the .30-30.
The 6.8mm has also been judged a satisfactory elk cartridge (!) by some excited scribes, a serious and unfortunate over-estimation of its capability. Its optimum game weight at the muzzle is only 435 pounds and the SD of its 115 grain bullet is simply inadequate for general use on CXP3 class game. The 6.8mm SPC should not be recommended to recreational hunters for use on CXP3 class game.
The 6.8mm SPC will doubtless be compared to existing 6.5mm cartridges. The trajectory of the 6.8mm SPC is slightly inferior to the trajectory of the .260 Remington and 6.5x55 SE when those cartridges are shooting 140 grain bullets, and is clearly inferior at all ranges in almost every other way. This includes bullet weight, SD, BC, wind drift, penetration, energy, and killing power. Again, the light 115 grain 6.8mm SPC bullet lacks the SD that makes the 6.5's all-around cartridges.
If trajectory is important, the 6.5mm's can be fed 120-125 grain bullets, shoot measurably flatter than the 6.8mm SPC with its 115 grain bullet, and still retain all of the advantages listed above. The 6.8mm SPC simply lacks the powder capacity of the .260 and 6.5x55 and can therefore never equal their performance.
None of this should be taken as a criticism of the 6.8mm SPC. It is merely a statement of physical fact. The new cartridge is superior to the 5.56mm NATO round in most respects and I would be very pleased to see it replace that cartridge as the main battle cartridge of the U.S. Army and Marine Corps.
With proper bullets the 6.8mm SPC should be an entirely satisfactory medium range cartridge for CXP2 class game. Handloaders will be able to somewhat increase its penetration, and presumably its reliable killing power, by using heavier 120-130 grain bullets. Both its trajectory and killing power indicate that it is potentially about a 265 yard deer cartridge.
The biggest advantage of the 6.8mm SPC, and one that should not be underestimated, is that its recoil and muzzle blast in a 7.5-8 pound hunting rifle with a 22" barrel should be quite low. The .270 Winchester will seem like a cannon by comparison. This is a primary concern of the military, and rightfully so. Its low recoil will also endear Remington's new cartridge to the once a year deer hunter, for whom it will be a good choice.
I can understand why Remington is introducing the 115 grain FMJ military-type load, but I fail to understand why they do not offer a 100 grain varmint/predator load using their Pointed Soft Point bullet (SD .186, BC .252). I would think that a 100 grain bullet could be driven at a MV of about 3000 fps. This would allow more versatility than a quartet of 115 grain factory loads, two of which are match bullets.
As most reloaders know, 115 grains is not a traditional weight for .277" bullets. Typical varmint bullets for .270 caliber rifles weigh 90-110 grains. Typical bullets for CXP2 class game (deer and antelope) weigh 120-140 grains. I would guess that reloaders will find bullets such as the Speer 90 grain TNT excellent for varmints and small predators. The 120 grain Barnes X-Bullet should represent just about the optimum weight for hunting deer, antelope, sheep, and goats given the case capacity of the 6.8mm SPC.
Here is some reloading data from the Hodgdon Powder Company:
Starting Load - 115 grain Sierra HPBT bullet, 26.0 grains of H322 powder, MV 2421 fps, 43,500 PSI.
As of this moment Remington has not announced any rifles chambered for the new 6.8mm cartridge. My suggestion is that the Model 760 pump plus the bolt action Model Seven SS and Youth, Model 700 Mountain Rifle, and Model 700 Titanium be the first offerings. These rifles would clearly be appropriate for the new caliber, although at least one factory load suitable for hunting CXP2 class game would be required.
The 6.8mm SPC has the potential to be a success both as a military and a civilian cartridge if the military brass and Congress permit its adoption. Since this cartridge was initially developed by soldiers, not the military hierarchy, that desirable outcome is by no means certain. I sincerely hope that the U.S. military and Congress will realize that it has potential far beyond its intended role as a "special purpose cartridge."
For North American deer hunters the introduction of a mild, medium range deer cartridge intended for use in autoloading and bolt action rifles is good news. The 6.8mm Remington SPC is a far more sensible choice for the great majority of U.S. deer hunters than any of the recent and much-ballyhooed short magnum cartridges.
My only real regret is that Remington adopted the "6.8mm" military-type designation for their civilian introduction of the new cartridge. I wish they'd given it a traditional American cartridge name such as ".270 Remington SPC."
Copyright 2004, 2012 by Chuck Hawks. All rights reserved.