I’ve read a number of articles about the origin of the 7mm Remington Magnum, but most of the writers either got it wrong or didn’t have a clue. The cartridge started life as a wildcat designed by famous Wyoming outfitter Les Bowman. Les was a good friend of mine and he told me he got interested in hot a 7mm after he guided Jack O’Connor on an elk hunt.
Jack showed his gratitude by giving Les the fine custom-built .275 H&H Magnum rifle with which he had taken a good elk. Les handloaded it to drive a 160gn bullet at 3000fps, but when he experienced difficulty in obtaining ammunition or brass for the .275 H&H, he started looking for a solution, which led to a series of lucky coincidences.
In 1956 Les heard that Winchester was ready to introduce a new cartridge called the .338 Win Mag, based on the necked-down .458 Win Mag case. He got Winchester to send him 200 cases without head stamps to experiment with.
About the same time, Remington sent Les two Model 721 rifles in .280 Rem calibre. One had an undersized barrel so he took it apart and shipped the action to Fred Huntington of RCBS, along with some cases he made by necking down Winchester .338 brass to 7mm, leaving the shoulder angle unchanged. Fred’s gunsmith fitted a 24” Pfeiffer barrel with 1:10” twist and provided a set of dies to suit. Les and Fred decided to call this wildcat the .280 Rem Mag.
After the rifle had been fitted with a beautiful fancy maple stock, Les developed a load which would drive the 160gn Sierra boat-tail bullet at 3000fps for long-range hunting. He wanted a load capable of reaching out 300-450 yards (ie, 400 metres and more) across wide canyons and deliver enough energy to drop a bull elk in its tracks.
He began using surplus H4831 powder which he and Jack O’Connor had been using to load their .270s. Once again fate intervened when Mike Walker of Remington sent Les a quantity of IMR7828, a new Du Pont powder with a slightly slower burning rate than H4831. Les found this powder produced excellent results, driving 160gn bullets at 3050fps.
FROM WILDCAT TO FACTORY FAVOURITE
Fate dealt him a winning hand once again when Walker and Wayne Leek turned up to go hunting at his Wyoming ranch. These men worked for Remington as gun designers and research engineers; Walker had been a national benchrest champion and Leek a top silhouette rifle shooter.
They not only spent a lot of time in the field, but also attended the annual seminars for gun writers, where they gained valuable information on the likes and dislikes of hunters and shooters. Both men frequently visited Les to hunt and often brought new Remington firearms to field test.
Naturally, Les showed them his wildcat .280 Rem Mag and allowed them to hunt with it. They liked it so much that they tried to persuade Remington to introduce rifles chambered for it. At first they encountered considerable resistance from Big Green’s marketing department, but they persisted until eventually the company decided to go ahead with production of Les Bowman’s wildcat, which they renamed the 7mm Remington Magnum.
The factory sent Les one of the first 700 BDL models with a 24” stainless-steel barrel and a 1:9¼” twist. Les told me that from 1962 to 1977 that rifle saw hard use and after firing 6300 rounds through it he sent it back to Wayne Leek, who fitted it with a barrel for the new 8mm Rem Mag. The rifle arrived back shortly before Les and I were to attend the 1978 Remington Seminar, but we had time to thoroughly wring out the big 8mm with Les loading the ammunition while I shot it for accuracy.
In total we fired over 300 rounds and not one five-shot group was larger than 1½”. The 8mm Rem Mag became my favourite cartridge and Remington gave me a 700 BDL that I hunted with successfully in the NT, Africa, India and Mongolia, but that’s another story.
Les Bowman achieved his desire of getting a cartridge that would carry more authority for long cross-canyon shots, and Remington sales skyrocketed.
I had my first 7mm Rem Mag built in 1976, a Model 98 Mauser fitted with a 24” barrel and fine classic-style walnut stock. I started shooting Norma factory ammunition in it. The 150gn Norma load was listed at 3260fps from a 26” barrel, but my rifle clocked 3160fps. Remington factory ammunition was loaded with either a 150gn PSP or a round-nosed 175gn Core-Lokt bullet at a nominal 3260 and 3020fps respectively. In my rifle the 150gn bullet was 150fps slower while the 175gn was actually a bit faster.
The ‘Big Seven’ proved to shoot as fast as the .270 Win but delivered 15 to 30 percent more energy away out yonder.
THAT WAS THEN, THIS IS NOW
The 7mm Rem Mag won an enviable reputation for all classes of North American big game, from antelope to moose, and my own experience has proved this reputation is well deserved. Today, there is a wide range of bullet weights and styles, virtually a bullet for every use, and for long-range shooting of heavy game. This doesn’t mean, of course, that they will all perform with equal efficiency, but the potential is there if their construction is right.
The high ballistic coefficients of .284 spitzer bullets weighing 160 to 175gn, coupled with good sectional density, ensures that few cartridges will shoot flatter or hit harder over long game ranges than a 7mm magnum.
Today, we have 7mm super magnums such as the 28 Nosler, 7mm STW and 7mm Ultra Mag, but in terms of rifle weight, modest recoil and less muzzle blast, the 7mm Rem Mag can hold its own in any company.
Reports from game fields all over the world made it inevitable that this highly effective cartridge would retain its popularity.
RELOADING THE 7MM REM MAG
Overall case length is listed at 63.50mm (2.500”) and maximum COL is specified as being 83.57mm (3.290”). But I held case length to 63.25mm (2.490”) or less and when the length exceeded this figure, the brass was trimmed back to 62.99mm (2.480”) and chamfered.
Having once-fired cases of several different makes on hand, I weighed them all to determine an average weight for each. Fired primers were left in, so that cases could be filled with water to determine internal capacity. The water-filled cases were then re-weighed, and weights of the empty cases subtracted from the weights of the water-filled cases, to discover the comparative interior capacities of each different brand of case.
The difference was surprising. The net weight of water varied by up to 5gn from the smallest to the largest case, which was Norma.
Micrometer readings of base diameters on fired cases were taken just ahead of the belt rather than over it for the simple reason that the belt is not reduced in diameter by resizing, whereas the body of the case gets sized down. When cases are reloaded a number of times, this method allows one to measure the amount of expansion caused by successive loads in the same brass and these measurements can vary considerably depending on brass hardness and case design.
The make of the cases, too, is a critical factor which can be eliminated by sticking with a single brand, or better still by buying brass that’s all from the same lot. Stay with a single make of case at least until you become familiar with the powders and loads in your rifle.
When you consider the variation in case capacity, the difference between barrels, cases, bullets and primers, it pays the handloader to take the maximum charges seriously and start with the lower loads listed for each powder and work up gradually, watching for pressure signs.
My first task was to establish a standard for ‘normal’ base-expansion diameter against which cases fired with handloads could be compared. Several different brands of factory cartridges were fired in my Mauser and their base expansion recorded.
Remington miked 13.099mm (0.5157”), Winchester Super-X 13.089mm (0.5153”), Federal 13.106mm (0.5160”) and Norma 13.114mm (0.5163”).
Based on these measurements, handloads that expanded between 0.5150” and 0.5160” were regarded as normal. Any above 0.5160” are considered to be near or at maximum, depending on the make of case and other indications of excessive pressure.
For example, Remington cases expanded beyond 0.5160”, or Federal cases measuring more than 0.5165”, and other signs such as cratered primers and an imprint of the ejector; indications that the practical limit had been reached. If the bolt handle is stiff to lift, it offers a further warning that pressures are far too high.
POWDERS AND LOADS
Powders chosen ranged from medium-slow to very slow, starting with AR2209, AR2213sc and AR2217. Later, I added AR2225. Back in the early 1990s I gained the highest velocity accompanied by moderate pressures using AR2214 (discontinued) with bullets weighing from 140 to 175gn.
Today, my best loads for the two most popular bullet weights are: the 140gn AccuBond and 68gn of AR2209 for 3274fps, and 68gn of AR2213sc with the 160gn Speer Grand Slam for 3000fps — taken in a 24” barrel.
Reduced loads in the 7mm Rem Mag can be achieved safely if a powder with the proper burning rate is chosen, but this is not why the big-game hunter buys a magnum in the first place. The main reason for using any magnum cartridge is to obtain more velocity than you can get with a standard case of that bore diameter using the same bullet weights. We do this to get a flatter trajectory at long range and in the case of the big-game hunter, more energy out where the game is.
In my experience it would be an unusual occurrence for a big case to give better accuracy with a reduced powder charge. I’ve found the best accuracy with a magnum cartridge always comes from near-maximum or maximum loads.
For this test series I picked several different loads with different bullets. While SAAMI maximum cartridge length for the 7mm Rem Mag is listed as 83.57mm (3.290”) the Remington Model 700’s magazine box length of 93.99mm (3.700”) allows handloads with extremely long bullets to be seated out farther.
To check chamber length I seated the Nosler 175gn AccuBond Long Range to the longest length that would chamber in the Remington 700 Long Range, which was 87.96mm (3.463”). The charge was 64gn of AR2217, which gave a muzzle velocity of 2820fps. Accuracy results with this load and a selection of hunting loads are listed in the table.
The 175gn Nosler AccuBond is a favourite of mine, combining the finest accuracy with the flat trajectory and wind-bucking ability that go with the high BC of .648 and muzzle velocity of 2900fps. A load of 65gn of AR2217 with this bullet proved the most accurate recipe of the series, grouping five shots well under an inch at 100yd. Sixty-eight grains of AR2225 nearly duplicated the target and at nearly the same velocity. I prefer this 175gn Nosler bullet mainly because if the only opportunity calls for a rear-end shot at an animal heading north, that bullet will hold together long enough to reach the boiler room.
About 40 years ago I expressed my opinion in print that the 7mm Rem Mag had turned out to be one of the best all-around, practical big-game hunting cartridges in the world. Nothing has happened since then to make me change my mind. The 7mm Rem Mag effectively combines high velocity, flat trajectory, power and deep penetration with moderate recoil.
In my opinion there’s no better all-round, multi-purpose big-game cartridge than the 7mm Rem Mag. Almost 60 years after its introduction, it still ranks among the top 10 hunting cartridges around the world, staving off challenges from bigger but not all that much better 7mm super magnums.
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