The North American 6.5mm Magnum Cartridges
By Chuck Hawks
The title of this article is not intended as some sort of jingoist statement. It happens there are some big case European 6.5mm cartridges that are almost never encountered in North America. Some of these, such as the 6.5x65mm RWS and 6.5x68mm RWS (Schuler) fall into the magnum performance category. However, factory loaded ammunition, and even reloading data, is virtually unavailable in the USA, where I live. Consequently, I am limiting this article to cartridges that are at least somewhat available to North American shooters.
As long time readers know, 6.5mm (.264 inch) cartridges are a favorite of the Guns and Shooting Online staff, and myself personally. Frankly, I prefer standard cartridges (not magnums) whenever possible, as they are usually entirely capable of doing whatever a particular caliber is good for and they produce less muzzle blast and recoil while doing it, which leads to more accurate bullet placement.
Magnum cartridges are often more sizzle than steak. Gaudy velocity and/or energy figures often do not translate into much (if any) advantage in real world killing power. Hunting should be about, well, ethical hunting, not long range sniping where bullets can, and often do, go astray.
In the case of 6.5mm cartridges, popular standard numbers, such as the 6.5x55mm, can drive 139-140 grain bullets at muzzle velocities from around 2735 fps (under SAAMI pressure limits) to 2850 fps (under CIP pressure limits). European CIP 6.5x55 loads are safe in Model 1896 Swedish rifles and all modern rifles, but are hotter than US SAAMI spec loads. SAAMI specifications unduly restrict many popular European cartridges, including the 6.5x55mm, 7x57mm and 8x57mm; an example of "home cooking," I guess.
In any case, a 139-140 grain bullet at 2600-2700 fps has long proven sufficient for hunting all Class 2 game and even large animals, such as Scandinavian moose. If outsize and/or dangerous game is on the menu, the 6.5x55 (and similar size cartridges, such as the .260 Remington and 6.5mm Creedmoor) can drive 156-160 grain bullet at MVs around 2500-2640 fps.
These heavy 6.5mm bullets can literally put down any animal on earth, so 6.5mm magnums bring little new to the table in terms of killing power. What they offer is somewhat extended range and flatter trajectory, plus bragging rights.
That said, we are in the midst of another period of "magnum mania," the second such in my lifetime. The first began in the late 1950s and peaked in the 1960s, by which time two of the cartridges included in this article were on the market: the standard (.30-06) length .264 Winchester Magnum and the short action (.308 Win. length) 6.5mm Remington Magnum. They were ahead of their time, as North American hunters at the time generally showed little interest in 6.5mm cartridges. The current, ongoing magnum mania bubble is a product of the 21st Century and coincides with an uptick in interest in 6.5mm cartridges.
140 grains has been the "all-around" and most useful bullet weight for all 6.5mm hunting cartridges worth their salt for about 100 years and it remains so today. With a sectional density of .287, there is plenty of potential for deep penetration and a very high ballistic coefficient with properly designed bullets. Heavier bullets (generally 156-160 grains) are required only for the very largest game, such as moose and polar bear, which in any case are best left to larger calibers.
.264 Winchester Magnum
Introduced in 1958, the .264 Win. Mag. was one of the original Winchester standard length, belted magnum cartridges and the first of the American 6.5mm magnums. The initial Winchester Magnum cartridges included the .264, .338 and .458 Winchester Magnums, all of which were intended for use in the standard, .30-06 length, Model 70 bolt action.
A long, and more expensive, magnum length action was required to accommodate the earlier .300 and .375 H&H Belted Magnum cartridges. This meant the standard length Winchester Magnums were adaptable to more actions. Savage, Remington and most other major manufacturers were soon offering mass produced rifles in the Winchester Magnum calibers.
Winchester's magnums were based on a shortened, blown-out and sharper shouldered .375 H&H case, the same basic formula earlier employed by Roy Weatherby a decade earlier when he created his .257, .270 and 7mm Weatherby Magnums, which are still popular today. However, at the time the Winchester Magnums were introduced, Weatherby was a specialty rifle manufacturer, not a major player as it is today, and the world was ready for mass market magnum rifles and ammunition from the likes of Winchester and Remington.
The .264 Winchester Magnum has a .532" rim and belt diameter, .513" head diameter and a 25 degree shoulder angle. The maximum cartridge overall length (COL) is 3.340 inches.
The .264 has always been a slow seller, but it has managed to stay in the Winchester rifle and ammo line. Factory loaded ammunition is also offered by Nosler and Remington.
Winchester and Remington each offer a single load using a 140 grain bullet, but Nosler offers several bullet weights, from 100 to 140 grains. Frankly, it is hard to see much point to bullets lighter than 140 grains in the .264, given its over-bore case capacity. A 140 grain bullet should be more than sufficient for most purposes, although the .264 is certainly capable of handling 160 grain bullets, which reloaders can drive at 2800 fps from a 24 inch barrel with a number of slow burning powders.
Winchester and Remington 140 grain factory loads currently claim a muzzle velocity (MV) of 3030 fps and muzzle energy (ME) of 2854 ft. lbs. from a 24 inch barrel and similar velocity can be achieved by reloaders. The original Winchester .264 Mag. factory load claimed a MV of 3200 fps from a 26 inch test barrel, so this is one cartridge that has not benefitted from being updated with the latest powders.
Burning a lot of powder and forcing it through a small bore has always been a prescription for short barrel life and this problem has plagued the .264 from its inception. When the .264 was introduced in 1958, shooters were aghast to find barrels showing accuracy degradation after only 1000 rounds. Today, young shooters seem to be ignorant, or simply not care, about barrel erosion. The latest 6.5mm magnums are significantly worse than the .264 in this area!
Whether the .264 Mag. is really any more useful than the .270 Winchester or the 7mm Remington Magnum, cartridges to which it has been compared for decades, is a moot point. Winchester admits that the .264's advantage lies primarily at ranges in excess of 400 yards. Needless to say, only a tiny percentage of hunters can shoot well enough, even from a rest, to justify 400 yard shots at medium size big game animals. Most hunters who attempt such shots wound far more animals than they bag, which is a horrific problem with all of the 6.5mm magnum cartridges, not just the .264 Winchester Magnum.
6.5mm Remington Magnum
The short action 6.5mm Rem. Mag. has been less successful than the .264 Win. Magnum. Remington rifles in the caliber were discontinued due to poor sales only a few years after its 1966 introduction in the Model 600 carbine, which came with an 18 inch barrel, if you can believe it. After the Model 600 and Model 660 (20 inch barrel) carbines were discontinued, the 6.5mm Rem. Mag. was offered for a few years in the Model 700 (24 inch barrel), a much more suitable platform, but the damage had already been done.
Based on a shortened 7mm Remington Magnum case, the 6.5mm Rem. Mag. case has the same .532 inch rim diameter, which is standard for belted magnums. Neck length is just about one caliber at .261 inch. The case length is 2.170 inches and the shoulder angle is 25 degrees. Overall cartridge length is specified as 2.80 inches.
The 6.5 Mag. was dropped from the M700 line due to disappointing sales and Remington factory loaded ammunition was discontinued between about 1994 and 2006. The failure of the 6.5mm Remington Magnum was apparently an example of a cartridge introduced ahead of its time, as 6.5mm cartridges were not popular in 1966 and no one at that time saw a need for magnum cartridges that would work in .308 length rifle actions, a situation that would not change until after 2001.
The 6.5mm Rem. Mag. would have been left for dead in the 1990s if Winchester had not introduced their WSM line of cartridges to considerable media fanfare in 2001. Remington quickly followed with their (unsuccessful) SAUM cartridges and then, seemingly as an afterthought in 2003-2004, reintroduced their original short magnum cartridges, the .350 Rem. Mag. and 6.5mm Rem. Mag.
Unfortunately, the 6.5mm Mag. is, once again, no longer offered in Remington Rifles or Remington brand ammunition. In 2016, among the major US ammo suppliers, only Nosler catalogs 6.5mm Rem. Mag. ammo and only in a single load using a 125 grain Partition bullet. The Nosler factory load claims 3025 fps MV and 2539 ft. lbs. ME from a 24 inch barrel.
According to the Nosler Reloading Guide (#7), reloaders can do better, launching a 125 grain bullet between 3217 fps and 3273 fps with four of the powders used (RL 19, RL 22, IMR 4831 and IMR 7828). 140 grain bullets can achieve MVs between 2997 fps and 3059 fps with the same four powders. This gives the 6.5mm Rem. Mag. about a 100-150 fps advantage over the 6.5mm-284 and 6.5mm-06, which are the biggest and fastest of the standard (non-magnum) 6.5mm cartridges.
Given that level of performance and the fact the 6.5mm Remington Magnum can be chambered in practically any short action rifle, of which there are about a zillion, you would think sales of Remington's 6.5mm offering would have taken off like a rocket. It is, to my way of thinking, the best and most useful of the 6.5mm magnums. It can handle all of the 6.5mm bullet weights, is very accurate and an outstanding long range cartridge. It is only slightly harder on barrels than a .270 Winchester, not a barrel burner like the .264 Win. Mag. or the outsize cartridges we will discuss next. Recoil is moderate, unlike the bigger magnums. Alas, most of the rifle buying public has never even heard of the 6.5mm Remington Magnum.
The .26 Nosler was introduced in 2014. It is based on a shortened Remington Ultra Mag (RUM) case, which is itself based on the fat .404 Jeffery elephant rifle case. Like the .264 Win. Mag., the .26 Nosler is designed to fit in standard length actions.
The maximum COL is 3.340 inches. Like most recent cartridge introductions, the case has very little body taper, a rather short neck and a sharp, 35 degree shoulder angle. The rebated rim diameter is .534 inch, while the case head diameter is .550 inches. Compare this to the .532 inch rim diameter, .513 inch head diameter and 25 degree shoulder of the .264 Win. Mag. and you can readily see why these fat cases with rebated rims do not feed as smoothly as conventional belted magnums.
The .26 Nosler was designed to be the fastest 6.5mm cartridge on the market and it was, for a couple of years, until the introduction of the 6.5-300 Weatherby Magnum (see below). Nosler factory loads, the only brand of ammunition available at this writing, launch a 140 grain AccuBond bullet at a MV of 3300 fps with 3385 ft. lbs. ME from a 24 inch barrel. This load allows a maximum point blank range (+/- 3 inches) of 325 yards, which is an increase of about 23 yards in MPBR compared to the .264 Win. Mag. shooting the same 140 grain bullet at a MV of 3030 fps.
The .26 Nosler is a very fast, flat shooting cartridge that burns a lot of powder. If the .264 Win. Mag. is a barrel burner, this is a super barrel burner. I would guess somewhere in the vicinity of 600-1000 shots before gilt-edged accuracy starts to fade.
It is unfortunate that the .26 Nosler is not offered with a 156-160 grain bullet. Given its great powder capacity, the heaviest bullets would seem to be the most logical choice to maximize killing power (and also barrel life, due to somewhat reduced velocity). Unfortunately, Nosler does not make a 6.5mm bullet heavier than 140 grains.
For reloaders, Nosler provides data in their #8 Reloading Guide and also online. The cartridge is also listed in the 2016 Hodgdon Reloading Manual. Neither source lists loads for 156-160 grain bullets. Nosler reloading information states, "As with all hyper-performance magnum cartridges, the .26 Nosler can be more exacting to reload than less over-bored rounds . . . powders with high load densities will work best . . . avoid reducing loads more than 5% from maximum."
The .26 Nosler was designed to work in .30-06 length actions, but this does not mean you can simply rebarrel a standard .30-06 rifle for the .26 Nosler. It requires a magnum bolt and, because of its fat case, an extra wide magazine with different feeding geometry.
As far as I know, the only source for new .26 Nosler rifles is Nosler. They offer their fine line of Model 48 semi-custom and custom rifles in a great many calibers, including .26 Nosler.
6.5-300 Weatherby Magnum
Announced in the 2017 Weatherby catalog, the 6.5-300 Weatherby Magnum is the fastest factory loaded 6.5mm cartridge in the world. Rather than use the oversize body diameter/rebated rim formula of the RUM cartridges and the .26 Nosler for their super 6.5, Weatherby necked-down the full length .300 Weatherby Magnum belted case. The rim is the standard .532 inch magnum diameter and the case head measures .512 inch. The case body has a bit more taper than the .26 Nosler to ease extraction from a dirty chamber, a pious idea. Maximum COL should not exceed 3.60 inches. Naturally, the 6.5-300 uses the famous Weatherby double radius shoulder.
The 6.5-300 Wby. avoids the potential feeding, extraction and magazine capacity issues of short, fat cartridges with rebated rims, but it requires a full length (.375 H&H size) magnum action. Since Weatherby, Winchester, Remington, CZ, Ruger and many others produce magnum length actions these days, this is not a major limitation.
Its full length magnum case also allows the new cartridge to have a long .2995 inch neck and plenty of case length to accommodate 156-160 grain bullets, although the initial Weatherby factory loads use only 127, 130 and 140 grain bullets. As of this writing, only Weatherby Mark V rifles and Weatherby factory loaded ammunition is available, but if 6.5-300 Mag. sales warrant it, I expect Norma brand factory loads will become available at some point in the future.
Weatherby advertises a 140 grain Swift A-Frame bullet at a MV of 3395 fps from a 26 inch barrel, the only barrel length available in Mark V 6.5-300 Magnum rifles. The ME is 3583 ft. lbs. Thus, the 6.5-300 outperforms the .26 Nosler by 95 fps and 198 ft. lbs. It should deliver an increase of about 10 yards in MPBR (+/- 3 inches) over the .26 Nosler and 33 yards compared to the .264 Win. Mag.
I seriously doubt this difference will matter to any game animal, but buyers of hyper-performance magnums are not interested in practicality. They are, presumably, primarily interested in bragging rights, regardless of muzzle blast, recoil, and very short barrel life. As with the .26 Nosler, the latter is likely to be around 600-1000 rounds for best accuracy.
Neither the .26 Nosler nor the 6.5-300 Weatherby have much practical advantage over the .264 Winchester Magnum, unless you consider an extra 23-33 yards or so of maximum point blank range absolutely necessary. However, if your ego demands the fastest of the 6.5mm Magnums, the 6.5-300 Weatherby is the cartridge of your dreams.
Copyright 2016 by Chuck Hawks. All rights reserved.