The Popular 7mm Remington Magnum

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When Winchester introduced the .338 in 1958 it was a foregone conclusion that some eager wildcatter would neck the case down to 7mm.

Just who was the first cab off the rank I don’t know, but more knowledgeable gun nuts believe that the credit belongs to Les Bowman. He told me the following story.

Back in 1949, Les had sold his business desdigning, manufacturing and selling commercial aircraft and moved to a ranch near Cody, Wyoming, where he set himself up as a big-game outfitter.

To the north and west of his ranch, was a high plateau from 9,500 to 13,000 feet above sea level that was used as summer range by a burgeoning herd of elk. Les called the place “Elk Heaven,” and told me that it was the long ranges encountered there that was largely responsible for his development of the 7mm Remington Magnum.

Elk Heaven was mostly above timberline; it consisted of a series of clear open ridges which made it hard to stalk close to the game. Most shots had to be taken from ridge to ridge at ranges from 300 to 450 yards.

For this reason Les was pretty careful to take only the most experienced hunters into Elk Heaven. He played host such dignitaries as Prince Abdorreza Pahlavi of Iran, together with a number of the most famous gun writers of that era – Jack O’Connor, Col. Charles Askins, Warren Page, Clyde Ormond and industry leaders like Fred Huntington of RCBS and Joyce Hornady. Each and every one of them took a nice trophy bull.

However, Les Bowman’s general run of clients were less successful, with many missing or wounding their elk. The problem, Les decided, was that too many hunters were using big .30 magnums and couldn’t handle the recoil without flinching. On the whole, those who used smaller calibres like the .270 and .30-06 did a whole lot better.    

Hunting with Les, Jack O’Connor cleanly killed a bull with his .270 and a 130gn bullet at close to 500 yards. He declared it was the longest shot he ever made on an elk. When he got home he showed his appreciation by sending Les a .275 H&H Magnum rifle that he’d had custom-made. Les used the rifle himself and loaned it to many of his hunters who had no trouble placing their shots accurately with handloads assembled to drive the Sierra 160gn SBT Sierra at 3000fps. While the Sierra bullet didn’t hold together and penetrate well at close ranges, it performed all right beyond 200 yards.

A year after Winchester brought out its .458 magnum, they advised Les at a seminar that they were going to bring out a new, .338 calibre on the same case. Les talked the factory’s R&D guys into letting him have 200 unprimed .338 cases to experiment with.

Coincidently, at about the same time in 1956, Remington had sent Les two Model 721 rifles in a new .280 Remington calibre. One had a barrel with a very tight bore, so he dismantled it and sent the action with a magnum bolt he had and some dummy cases he made by simply necking the .338 cases down to 7mm with no change in shoulder angle, to Fred Huntington at RCBS in Oroville California. Les asked Fred’s gunsmith to install a 24 inch Pfeiffer 7mm barrel with 1:10 twist and chamber it for his wildcat 7mm/338.

Fred had RCBS make up a set of loading dies which were stamped “.280 Rem. Mag,” and Les had the rifle stocked in fancy tortoise shell maple by California stockmaker Carl Peterson. Years later I shot this rifle at the Bowman ranch in Ocate, New Mexico. It was a beautiful, well-balanced rifle and very accurate into the bargain.

Just as a matter of interest, another experimenter called an identical wildcat the 7mm Belted Newton because it was similar to the experimental cartridge Charles Newton tinkered with, but never produced before World War I – a 7mm on the big .30 Newton case.

Two of Remington’s design team, Mike Walker and Wayne Leek were close friends with Les Bowman. They saw and shot Bowman’s “.280 Remington Magnum” and were mighty impressed with it.

Les had been loading the cartridge with Hodgdon’s surplus H4831, but Mike Walker sent him a supply of a new unnamed slightly slower powder (IMR7828) to use with the Remington 165gn soft-point bullet. Les later found this powder was ideal for use with long, heavy 175gn bullets, but believed that the criterion of what any 7mm magnum would do was with a well-constructed 160gn spitzer bullet.

Using the new powder, Les obtained 3,050fps with the 160gn Sierra bullet and loaned the gun to many of his hunters who used it to take elk, moose, bear and deer with great success. Mike Walker and Wayne Leek soon realized the commercial potential of the .280 Mag. and tried to influence Remington to bring out rifles chambered for it.

At first, Big Green’s bean counters, turned the suggestion down flat quoting how poor sales of the 7mm Weatherby had been. Les countered by telling them that its lack of popularity was because of the rifle’s 1:12 twist which was too slow to stabilize long, heavy 160 and 175gn big-game bullets. 

Following the 1960 Remington seminar, Les met with Tom Coleman, the President of Remington and tried to convince him of the merits of his .280 wildcat. A few days later, Les received word from Remington that they’d decided to put his cartridge into production, call it the 7mm Remington Magnum, and bring it out in their new Remington Model 700 ADL and BDL magnum rifles.

The combination took off like a house on fire and proved so successful that Remington was unable to catch up with the demand for several years. Both the Model 700 and 7mm Rem. Mag., celebrated their 60th anniversay last year.

Jack O’ Connor said that Remington Arms had been interested in such a cartridge for a long time, and that he had seen at the Remington ammunition factory at Bridgeport in 1940 an experimental 7mm magnum cartridge that was about identical to the  .280 Dubiel or the German 7x73mm Vom Hofe, both of which are basically the .300 H&H case necked down to 7mm.

Factory ammunition was initially loaded with a 125gn PSP Core-Lokt, a 150gn PSP Core-Lokt bullet and a 175gn round-nose Core-Lokt bullet at muzzle speeds of 3430fps, 3260fps and 3030fps respectively.

Published velocities were taken in a 26 inch barrel and as a conseqence factory velocities produced in the Model 700’s 24 inch barrel were somewhat lower – 125gn about 3250fps; 150gn 3135fps and 175gn 3070fps. Still nothing to be sneezed at.

The late Bill Marden built my first 7mm Rem. Mag. by installing a Douglas barrel with 1:9 twist ( Remington 700 has 1:9-1/4” twist) in a Mauser 98 action and Keith Herron supplied H4831 powder for 3 quid a pound.

A fired 7mm Remington Magnum case of Remington make held 74gn of water filled to the base of a 154gn Hornady bullet, a Federal case held 75.8gn. and a Winchester-Western case held 74gn. But then I discovered that Norma cases had a larger boiler room than any other brand of brass – 78.8gn. Such a substantial difference in the capacity of 7mm magnum cases was confusing and called for great care when reloading.

The need for comparative measurements of case weights and capacities is critical, as is brass hardness and case design, since they are partly responsible for the unusual variations I’ve found with 7mm Rem. Mag. loading data. Even today, I’d recommend sticking with just one make of case and, if possible try to ensure that all brass comes from the same lot.

Other variations are, I have found, caused by different barrel lengths, rifling twists and throat lengths. All these things explain why maximum loads in different manuals vary so much – on the average by 5 grains!

Out of seven manuals I checked, four used a 24 inch test barrel, three a 26 inch barrels. Four used Remington cases, one Winchester, and two listed Norma brass. But they also used different primers. Two sparked their loads off with Remington 9- 1/2Ms; one, Federal 215; two, CCI 250s; one CCI 250s; and one the standard WLR.

Another important factor. Years ago bullets all had pretty much the same construction – lead core and copper alloy jacket. Nowadays, some 7mm bullets are made with copper alloy jackets and have cores of different hardness. Some bullets like the Barnes TSX and Hornady GMX made of solid copper or gilding metal which leads to bullets of the same calibre and weight with differing lengths, hardness and bearing surface. They also have different shapes and manufacturing techniques and pressures can vary widely – over 8000 psi in some instances.

Obviously, such a diversity of barrels and components accounts for the wide variation in published ballistic results. I’d also issue a warning to handloaders that no matter which manual they use, they should take seriously the maximum loads listed, and whether or not they are using the same or different components, always start with the lowest loads listed with each powder and work up one grain at time watching for pressure signs.

I started out by loading the 7mm Rem. Mag. with the 160gn Speer and Nosler bullets and the 154gn Hornady bullets and 72gn of H4831. Pressures seemed moderate. Velocity was 3140 fps. With the 175gn Speer, a charge of 70gn of H4831 produced 2985fps – still with normal pressure.

My suspicion that my rifle was capable of consuming unusually heavy charges was later confirmed when I took the rifle to New Zealand and assembled the ammo for my hunt using an unfamiliar powder scale. Despite being overloaded by 10 grains of powder, the rifle never made a hiccup.

For deer hunting, in 1991, I developed a load with the 140gn Nosler Solid Base BT and 70gn of Re-22 that produced 3260fps. It not only shot very flat, but was a spectacular performer, dropping fallow bucks and large boars like the hammer of Thor.

A good load for goats and predators turned out to be the 130gn Speer and 71-1/2gn of Re-22 which churned up 3390fps.

A handload I’ve used a great deal in my custom Mauser and a post-64 Winchester Model 70 is the Remington 150gn Core-Lokt bullet and 65gn of AR2209. It has given excellent hunting accuracy while providing good expansion and deep penetration. That Core-Lokt bullet may be an oldie, but it’s a goodie and has never let me down.

Alas, I can’t say that about some of the modern plastic- tipped bullets I’ve used. Many groups run less than one inch. Velocity is a surprising 3255fps in a 24-inch barrel. With slow- burning Re-22 a charge of 71-1/2gn gives the Core-Lokt bullet 3225fps – or about the same as with AR2209, although pressures seem a little milder.

Overall, I have concluded that AR2213SC and RE-22 are best suited to this cartridge. They both did better than IMR 7828 with the heavier bullets filling the powder space nicely without having to be heavily compressed. With bullets of 150gn and less, I got excellent results with AR2209, but even with the light 120 and 130gn bullets I obtained higher velocities with RE-19 and Re- 22.

A neighbour of Les Bowman’s was getting 3200fps in a 550mm barrel with the 140gn bullet in front of 68gn of IMR4350. Pressure was probably right up there. The 130gn Speer and the various 140-grainers can be moved along at between 3200 and 3350fps, and proved to be spectacular killers on New Mexico’s deer and antelope at longish ranges.

When sighted in 3 inches high at 100 yards, the 150gn load was only a couple of inches low at 300 and down only 10 inches or so at 400. Thus a backline hold on a deer at 400 resulted in the bullet landing dead centre in a red stag’s chest. Zeroed the same, the .270 Winchester 130gn load at 3060fps was down about 15 inches the same distance.

He told me that he soon learned that the 150gn PSP Core-Lokt was more effective and suited him better than the 175gn round- nose loaded at that time (1966) by Remington. The heavier bullets expanded too slowly, and on lung shots and most of the animals he hit with it traveled from 50 to 100 yards before going down.

Some pretty fanciful stuff has been written and bragged about on the 7mm Rem. Mag., some pro and some con. I have learned to apply a liberal pinch of salt to most such reports.

I have no doubt that there are others who have had a lot more experience with the 7mm Rem. Mag. than I have had, but I have shot enough game with the cartridge so that I feel I know something about it. I have seen it used on moose and elk and shot a few deer and boars with it. Back in the late 1960s when I visited friends in New Mexico the 7mm magnum was still new.

I went out with a rancher in the Ocate valley who had a Model 700 equipped with a 3-9x Redfield scope. Shooting Remington factory ammo with the 150gn PSP Core-Lokt he knocked off a 12-point bull elk at a good 400 yards as I watched through my binocular. Hit through the lungs, the bull dropped on the spot.

I can remember one long shot I took on a rusa stag in New Caledonia. From memory it must have been at least 350 yards. On another occasion I watched a hunter in Alaska score a one shot kill on a trophy moose at around 225-250 yards. He later took a shot at a handsome Barren Ground bull caribou at a similar distance, and it went down so fast that he lost sight of it when the rifle recoiled.

Les Bowman always claimed, and with good reason, that the 7mm magnum is a better long range cartridge than the .270 Winchester. The 7mm can drive a 140gn bullet 100fps faster than the .270 does a 130gn, and retains 245 fps more velocity at 400 yards. And it shows an advantage in striking energy of 33 percent at that distance. But the 7-mag starts its ballistically more efficient 160gn spitzer bullet at 2950fps against 2850fps for the 150gn .270. But the 7mm magnum delivers 1581 ft/lbs of energy at 400 yards against only 872 ft/lb for the .270.

It would be a fairer comparison to compare the 7mm Rem. Mag. with the .270 WSM which lofts out a 150gn bullet at 3100fps and retains 2430fps and 1705ft/lbs at 400 yards. Or the 7mm WSM which actually has a slight edge, since the 160gn Barnes TSX which leaves the muzzle at 2990fps is still traveling at 2290fps and delivering 1885 ft/lb at 400 yards.

While Weatherby’s .270 and 7mm magnums show an even bigger edge over their competitors, such comparisons are largely a waste of time.

When reloading, a close watch should be kept on the expansion ring, which signals approaching danger of a case separation. If, after four or five firings, some of my cases show a bright ring, they are immediately junked. Even a partial head separation at the high 60,000 psi-plus pressures in this cartridge is most undesirable and potentially dangerous to both rifle and shooter.

When reloading any belted case I have often recommended that you do not turn the full-length sizing die down to touch the shellholder. Instead back it off from one-quarter to one-half turn as needed to size case necks, without forcing the shoulder back. The amount of back-off will depend to some extent on each rifle’s individual chamber and maybe the dies as well. With my rifle and RCBS die, a quarter turn back-off is enough to size case necks and bodies without affecting shoulder location.

Once you have established the correct die setting, belted cases will headspace on the shoulder rather than the belt and can be resized and reloaded just like rimless cases. Furthermore, unless reloaded too many times, case separations will be a thing of the past.

How long the 7mm Rem. Mag. will manage to hang on to a reputation for being our most popular magnum cartridge is anybody’s guess, but I don’t expect to see it dethroned anytime soon. New cartridges like the 7mm WSM, 7mm SAUM, 7mm STW, 7mm Dakota, and 7mm Ultra Mag have arrived to threaten its supremacy, but when you take into account all the thousands upon thousands of rifle in 7mm Rem. Mag. still being used on big game, the grand old cartridge is going to be around for a long time yet.

I doubt there’s any other cartridge (unless it’s one of the other 7mm magnums) that so effectively combines high velocity, flat trajectory and hitting power with moderate recoil as does the 7mm Remington Magnum.

Long may it reign.

This article was first published in the Sporting Shooter April 2014 issue.

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