The 6.5mm-284 Norma and 6.5mm Remington Magnum
By Chuck Hawks
The 6.5mm-284 Norma and 6.5mm Rem. Mag. are well regarded cartridges among savvy riflemen, particularly those specializing in long range shooting. These cartridges are comparable in performance, but they are based on very different cases.
The 6.5mm Remington Magnum was the second of Remington's original short magnum cartridges, introduced in the mid-1960's for use in their Model 600 bolt action carbine. This is a hunting cartridge designed for use in hunting rifles. The 6.5-284 Norma's parent case, the .284 Winchester, was introduced in 1963 by Winchester for use in their Model 88 lever action and Model 100 autoloading rifles. Both of these cartridges were intended to provide what was essentially .270 Winchester ballistics from short (.308 Win. length) actions.
The 6.5mm Remington Magnum was formed by necking down the .350 Rem. Magnum belted case. (Actually, any standard belted magnum case can be used as the basis for forming 6.5mm Rem. Mag. brass.) It uses a standard belted case with a .532" rim diameter and .513" head diameter. The case length is 2.170", the shoulder angle is 25 degrees and the cartridge overall length (COL) is 2.800". The 6.5mm Mag. was standardized by Remington to SAAMI specifications with a MAP of 53,000 cup.
While the original .284 Winchester cartridge never caught on, wildcatters immediately seized upon the .284 case and necked it up and down. Perhaps the most successful and enduring of the .284-based wildcats was the 6.5mm version, which became a very successful match cartridge. This cartridge achieved considerable popularity as a wildcat, where it was known as the "6.5mm-284 Winchester" or simply the "6.5mm-284." Having been a wildcat cartridge for most of its life, the precise chamber dimensions of 6.5mm-284 custom built rifles may vary, but the most common approach was simply to neck-down the .284 Winchester case without any other changes.
A few years ago Norma of Sweden picked-up on the increasing popularity of the 6.5mm-284, got the cartridge standardized by the European CIP, loaded it with Nosler bullets and introduced it in their ammunition line. Now that it has been standardized, the former wildcat's proper name is "6.5mm-284 Norma." The .284 Winchester was standardized by the SAAMI at the very high Maximum Average Pressure (MAP) of 54,000 cup and the 6.5mm-284 Norma is presumably loaded to similar pressure. Specialty ammo makers Stars & Stripes and Nosler now offer custom factory loaded ammunition in 6.5mm-284. Norma also sells virgin 6.5mm-284 brass for reloading, as does Lapua of Finland and perhaps others. All of the major manufacturers of reloading dies offer the caliber.
The .284 Winchester case upon which the 6.5mm-284 is based is a rebated rim design with a cartridge overall length of 2.800" and a very sharp 35 degree shoulder angle. It has the .473" rim diameter of a standard rimless case, but a head diameter of .500". Thus, its head is fatter than its rim (a rebated rim). This case style is satisfactory for a single shot bolt action target rifle (the primary application for the 6.5mm-284), but has serious drawbacks for repeating hunting rifles, as both the rebated rim and sharp shoulder degrade feeding reliability.
The 6.5mm-284 Norma case length is 2.170" and the shoulder angle remains 35 degrees. A cartridge overall length of 2.8" is required for use in the magazines of short action repeating rifles. Single shot 6.5mm-284 target rifles are often reamed with throats that allow seating 140+ grain bullets farther out for a longer COL. For example, the Sierra reloading manual specifies a COL of 2.910" with their popular 142 grain HPBT MatchKing bullet and the Nosler guide specifies a COL of 3.310" for the 6.5-284 Norma (longer than the popular 6.5x55!).
The 6.5mm-284 has become the cartridge of choice for long range (600-1000 yard) target shooting. It now dominates both NRA Long Range High Power (where in recent years it has been used to win the Leech and Wimbledon Cups) and F-Class Open matches and seems likely to maintain its position as the premier long range cartridge for many years.
In both performance and case capacity the 6.5mm Rem. Mag. and 6.5-284 Norma are between the .260 Rem. and the .264 Win. Mag. They shoot flatter than the .260 Remington and kick less than the .264 Mag. Shooting reasonable loads, barrel life is also better than the .264 Magnum, although with maximum loads the 6.5mm-284, in particular, has a reputation as something of a barrel burner in its own right. No doubt this is because it is primarily a target rifle cartridge and fractions of a MOA can matter at the highest levels of competition. A barrel that has fired about 1000-1200 rounds is usually considered to be past its useful life, although it may still shoot satisfactorily for big game hunting. Here are the case capacities of our two cartridges.
Despite their excellent long range ballistics, neither of these are popular hunting cartridges nor is there a plentiful supply of factory made rifles. Over the years, Remington has offered some of their bolt action carbines (Model 600, Model 660) and rifles (Model 673, Model 700) in 6.5mm Magnum caliber and Savage offers their production F-Class Open target rifle in 6.5mm-284 Norma. The great majority of 6.5mm-284 target rifles are custom built.
Among the major ammo manufacturers, factory loaded ammunition for the 6.5mm Mag. is available only from Remington, loaded with a 120 grain Core-Lokt PSP bullet (BC .323). Factory loaded ammunition for the 6.5mm-284 is available only from Norma, loaded with a 120 grain Nosler Ballistic Tip bullet (BC .458) or a 140 grain Nosler Partition bullet (BC .490). Here are the common factory load ballistics for the 6.5-284 Norma and 6.5mm Rem. Mag. taken in 24" test barrels (velocity in feet per second / energy in foot pounds).
As might be expected by their very similar case capacities, there is not much difference in the ballistics of these two cartridges as factory loaded. The superior ballistic coefficient (BC) of the 120 grain Nosler bullet compared to the 120 grain Remington bullet accounts for what difference there is down range.
Due to the scarcity of factory loads, these are primarily reloaders' cartridges. Reloaders can essentially duplicate the factory loads listed above by shooting maximum loads in long barreled rifles. Bullets as light as 95 grains and as heavy as 160 grains can be used, although the popular bullet weights for hunting or target shooting are between 120 and 142 grains.
Published reloading data in the Hodgdon, Hornady, Lyman, Nosler, Sierra and Speer reloading manuals for these two cartridges varies considerably. This is no doubt partly because 6.5mm-284 rifles usually have barrels from 26" to 32" long and most 6.5mm Rem. Mag. hunting rifles are carbines with 18.5" or 20" barrels. The longest barrel supplied on a factory built 6.5mm Rem. Mag. rifle, to the best of my knowledge, was the Model 700 BDL with a 24" barrel and the most recent offering was the Model 673 with a 22" barrel. The longest length listed for a 6.5mm Rem. Mag. barrel in any of my reloading manuals (Hodgdon in this case) is a 26" pressure test barrel.
Depending on whose data you use, in 26" barrels the various 120 grain bullets can be driven to a maximum MV of about 3100 fps in the 6.5mm-284 (Sierra figures, with two powders) and at 3286 fps in the 6.5mm Rem. Mag. (Hodgdon figure, with only one powder). For a hunting rifle with a 24" barrel, loading for a MV of 3000 fps in the 6.5mm-284 and 3100 fps in the 6.5mm Magnum would seem reasonable.
140 grain bullets in the 6.5mm-284 Norma can be driven to a MV of 2924-2925 fps from a 26" barrel by two powders according to the Nosler reloading guide, or to 2901 fps by one powder according to Hodgdon figures. F-Class long range target shooters typically load their 6.5mm-284 rifles very hot and are achieving about 2950 fps from 30" barrels.
The Hornady manual shows that four powders can drive their 140 grain bullets at a MV of 2900 fps from a .350 Rem. Mag. rifle with a 24" barrel. I would consider 2900 fps from a 24" barrel about the maximum practical MV for either caliber. Here are some trajectory figures (in inches) for the Hornady 140 grain A-Max bullet (BC .550) at a MV of 2900 fps zeroed at 200 yards, 600 yards and 1000 yards.
These figures are humbling. They illustrate not only the extreme capability of our hot 6.5mm cartridges, but also how difficult long range shooting is with any cartridge, even the world's premier long range match cartridge. From the hunter's perspective, a bullet from a hot 6.5mm Magnum deer rifle zeroed at the usual distance of 200 yards will hit nearly 7" low at 300 yards; he will need to aim along the animal's spine to put his bullet into the heart/lung area. If he were so foolish as to try a shot at 600 yards, he would have to hold approximately 5-1/2 feet over his target!
On the other hand, if our hypothetical hunter anticipated shooting at long range and zeroed his rifle at 600 yards, he would shoot completely over the top of a deer that appeared at 200 or 300 yards; he would have to remember to hold a couple of feet under where he wanted to hit. Moreover, if his deer were 800 yards away instead of 600, he would have to hold 5 feet over where he wanted to hit! The bullet's 14+ foot drop at 1000 yards is too depressing to contemplate. And remember, this is shooting the ultra-low drag A-Max match bullet, not an ordinary hunting bullet. Ponder those numbers for a while and then decide if you still believe the stories you read in the sporting magazines about ultra-long range big game kills.
Trajectory is not the entire story, of course. Other factors are also important, particularly for the hunter. Sectional density (SD), the ratio of a bullet's weight to the square of its diameter, is an important factor in penetration and thus the length of the wound channel and killing power. 6.5mm (.264" diameter) bullets shine in this area. The sectional density of a 6.5mm/120 grain bullet is .246, slightly superior to the .242 SD of a 130 grain .270 bullet and practically identical to the .248 SD of a 165 grain .30 caliber bullet.
The sectional density of a 140 grain 6.5mm bullet is .287, which is considerably better than the .271 SD of a 180 grain .30 caliber bullet and nearly identical to the .288 SD of a 230 grain .338 bullet. The excellent SD of 6.5mm hunting bullets has made the caliber's reputation as a slayer of big game animals. It also contributes to the high ballistic coefficient of 6.5mm match bullets.
Recoil, or its absence, is another factor in the popularity and effectiveness of 6.5mm rifles. The 6.5mm-284 Norma and 6.5mm Rem. Mag. shoot as flat as a .300 Magnum with bullets of equal or superior SD, yet kick far less. It is no secret that anyone can shoot better with a rifle that kicks less. Here are some recoil energy (in foot pounds) and velocity (in feet per second) figures for 6.5mm-284 and 6.5mm Rem. Mag. rifles weighing 8 and 15 pounds.
As the above figures show, you get a lot of performance for the price (in recoil) with these 6.5mm calibers. That, in a nutshell, is why the 6.5-284 has displaced the various .300 Magnums in the exacting sport of ultra-long range target shooting. The world's best riflemen know that less recoil translates to higher scores and knowledgeable hunters have learned that less recoil puts more meat in the freezer.
Summary and Conclusion
These hot 6.5mm numbers are superior long range cartridges. They offer a nearly optimum balance of characteristics, including low recoil, high velocity, flat trajectory, excellent sectional density and ballistic coefficient, adequate bullet weight and high retained energy downrange. The acceptance of the 6.5mm-284 among target shooters is understandable, since it uses the sort of short, relatively fat case upon which they dote. It is a design well adapted to single shot bolt action rifles. Match grade brass, while expensive, is available from Norma, Lapua and possibly others.
Why long range target shooters have not discovered the 6.5mm Remington Magnum as an attractive alternative to the 6.5mm-284 is something of a mystery to me. The two cartridges offer essentially identical performance. Perhaps it is because Remington has never produced match grade brass for their short magnum. It seems to me that Remington is missing a bet by not producing match loads and match grade brass for the 6.5mm Magnum--and promoting both. Perhaps an F-Class Open version of the 40XB target rifle would also be in order. (Many custom built F-Class rifles are based on a Remington action.) Savage Arms is producing excellent F-Class target rifles and sponsoring shooters. Could Remington not do the same? The way things stand, if NRA Long Range High Power or F-Class Open competition is your goal, the 6.5mm-284 Norma is the best choice.
The balance swings the other way if you are looking for a long range hunting cartridge. The 6.5mm Rem. Mag. is a better design than the 6.5mm-284 Norma for feeding from the box magazine of a repeating hunting rifle. It has also been around longer as a factory standardized cartridge and there are more factory produced rifles available on the used market. Remington ammunition is more widely distributed than Norma ammunition in the U.S. and usually less expensive. For the reloader, if cases must be formed, there are a great number of belted magnum cases from which 6.5mm Rem. Mag. cases can be formed, compared to the limited supply of .284 Win. brass needed to form 6.5mm-284 cases.
As we have seen throughout this article, choosing between these two cartridges really comes down to the intended application. The way things stand as I write these words, if you are looking for a long range match cartridge, go with the 6.5mm-284 Norma. If you are looking for a cartridge for a hunting rifle, the 6.5mm Remington Magnum is the better choice.
Note: A comparison of the 6.5mm-284 Norma and 6.5mm Rem. Mag. can be found on the Rifle Cartridge Page.
Copyright 2007 by Chuck Hawks. All rights reserved.