The 7mm STW - Still Holding Its Own

They say time flies when you’re having fun. Perhaps that’s why it does not seem like 30 years have passed since my introductory article on the then-new 7mm Shooting Times Westerner wildcat appeared in the May 1988 issue of Shooting Times.

That first rifle, built by Kenny Jarrett in August of 1987, has “7mm STW No. 1” engraved on its floorplate and was built around a blueprinted Remington Model 700 action. It also has a McMillan stock. The first 7mm STW chamber reamers were made by Henriksen Tool Co. The rifle still wears its original Schneider barrel, and with its favorite loads, it still averages less than 0.50 inch for groups fired at 100 yards.

Many new 7mm STW powders, bullets, and factory loads have been introduced during the past three decades, and for checking out their performance for this anniversary report, I chose a Model 52 Open Country Long Range from Cooper Firearms of Montana. The rifle comes standard with an extended single-stack magazine that holds five rounds. The rifle’s 26-inch barrel measures 0.75 inch at the muzzle, and it wears a very efficient 30-port brake. The trigger breaks at 32 ounces with no detectable creep or overtravel. During my accuracy tests, Warne rings held a crystal-clear 4-16X 50mm Nikon Monarch 3 scope securely to the rifle’s 10-MOA Picatinny rail. The scope came with Nikon’s interchangeable elevation turrets for the bullets I’ll be using in my custom Ruger No. 1 in 7mm STW. More on that rifle later.

Recent Advancements

One of the more interesting advancements during the past 30 years is a new crop of high-ballistic-coefficient bullets. Examples are the Nosler AccuBond LR, Hornady ELD-X, Berger VLD Hunting, and the Barnes LRX. I welcome them, not because they guarantee shooters will consistently take game cleanly at insane distances (because they do not), but because their high ballistic coefficients enable those bullets to better resist wind deflection and deliver more energy to the target. And that helps real hunters make clean kills at ethical distances.

A big difference between the old and new bullets is that the extremely long ogives of the new bullets require some of them to be seated quite deeply into the case in order to keep cartridge overall length compatible with magazine lengths. The result is reduced net case capacity and increased freetravel compared to bullets from an older school. This applies to all cartridges, including the 7mm STW. With the Hornady 175-grain ELD-X seated to an overall cartridge length of 3.615 inches (maximum for the magazine of the Cooper rifle), freetravel was 0.136 inch.

I have not worked with all the new bullets, but I have tried several in six 7mm STW rifles, and considering the amount of freetravel, accuracy has ranged from acceptable to excellent. Old-school bullets with shorter ogives can be more accurate in some rifles, but the difference is not always great. Expanding bullets of monolithic construction often carve out tiny groups with plenty of jump, and while some lead-core types don’t, others do. Some rifles tolerate plenty of jump, while others don’t. Punching paper will tell the story for a particular rifle and bullet combination.

Some of the new bullets are too long for use in the magazines of repeating rifles. The Berger 195-grain Elite Hunter at 1.635 inches is an example. Berger recommends a cartridge length no shorter than 3.759 inches for the 7mm STW. Absolute maximum cartridge lengths for Winchester Model 70 and Remington Model 700 magazines are 3.600 inches and 3.660 inches respectively. The Hornady 175-grain ELD-X at 1.575 inches is magazine-friendly, but it occupies a lot of powder space inside the case. Even so, the latest Hornady manual shows it moving along at 3,000 fps from a 26-inch barrel. The 168-grain LRX is 1.595 inches long, and according to Barnes, its highest velocity from a 24-inch test barrel was 3,067 fps at a cartridge length of 3.600 inches.

The chamber throat of my custom Ruger No. 1 was reamed long enough to allow the new extra-long bullets to be seated out of a case for minimum intrusion on its powder cavity. And since the rifle has no magazine, there is no limit on overall cartridge length. When seated to a length of 3.921 inches, the 195-grain Berger freetravels 0.030 inch prior to engaging the rifling. The Hornady 175-grain ELD-X is most accurate in my Ruger when seated 0.060 inch off the rifling at an overall cartridge length of 3.852 inches. The Barnes 168-grain LRX seated 0.105 inch off the rifling at a cartridge length of 3.781 inches also delivers excellent accuracy from my Ruger No. 1.

Seating the Berger and Hornady bullets with their bases in the vicinity of the shoulder/neck juncture of the 7mm STW case allows almost 100 percent of its capacity to be utilized. The Barnes bullet does use up some space but seating it out as much as possible proved to be beneficial. While doing so with those three bullets allows the use of slightly heavier powder charges for increased velocities without exceeding maximum pressures in my rifle, the powder charges used would surely generate excessive pressures in rifles with standard-length chamber throats. The additional powder burned in my Ruger No. 1 increases velocity by about 100 fps compared to a standard chamber. The 30-inch barrel is about 150 fps faster than a 24-inch barrel and 100 fps faster than a 26-inch barrel. Add it all up and total velocity gain ranges from 200 to 250 fps. Overall length of a Ruger No. 1 with a 30-inch barrel is the same as for a long-action Remington Model 700 with a 26-inch barrel.

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Keep in mind that some of the longer bullets may require quicker rifling twist rates than we are accustomed to using. Whereas twist for rifles chambered for the 7mm STW is usually 1:9, Berger considers 1:8.3 optimal for the 195-grain Elite Hunter, and Barnes says 1:8 for the 168-grain LRX. But since bulletmakers tend to be a bit conservative when recommending twist rate, along with the fact that mass-produced barrels can vary a bit from their makers’ specifications, you will never know for certain about a particular bullet until you try it in your rifle. Hornady recommends no slower than 1:8.5 for the 175-grain ELD-X, and while accuracy was quite acceptable from the 1:9 twist of the Cooper Model 52 barrel, a quicker twist would likely shrink group size.

Since I first wrote about the 7mm STW, military surplus H870 powder has been replaced by newly manufactured US 869, and Accurate 8700 has been discontinued. Other new propellants include Retumbo, IMR 7977, IMR 8133, Reloder 25, Reloder 26, Reloder 33, Reloder 50, Ramshot Magnum, Accurate MagPro, and VihtaVuori N570. Nowadays, I seldom use bullets lighter than 160 grains, and my picks among the new propellants for both accuracy and velocity are IMR 8133 and Reloder 33. Regardless of the powder used, I continue to prefer the Federal 215 primer.

Federal is the only member of the big three that continues to load the 7mm STW cartridge on a regular basis. This has been good news for smaller manufacturers, with the owner of one of them recently stating, “We sell truckloads of 7mm STW ammo.” They include Precision Cartridge, Double-Tap, Hendershot’s, HSM, Choice Ammunition, Nosler, and Georgia Arms. I shot ammo from the latter four along with Federal in the Cooper Model 52 rifle, and the outstanding results are listed in the accompanying chart.

Frequently Asked Questions

One of the more common questions I have been asked through the years is why some reloading manuals show the 7mm Weatherby Magnum, which has close to the same powder capacity as the 7mm Remington Magnum, exceeding the velocity of that cartridge and equaling the 7mm STW. The short answer is freeboring. In early Weatherby rifles it ranged from 0.500 to 0.750 inch and was eventually reduced to 0.378 inch for the 7mm Weatherby Magnum. Requiring a bullet to freetravel quite some distance prior to engaging the rifling allows the use of more powder for increased velocity at no increase in chamber pressure. Data published in most handloading manuals for the Weatherby cartridge are from barrels with freebored chambers, while barrels chambered for the Remington cartridge have chamber throats of standard length.

All else being equal, if bullet jump in rifles in 7mm Remington Magnum and 7mm Weatherby Magnum is the same, maximum loads in both will deliver close to the same velocities at similar chamber pressures. This is clearly illustrated by data shown for the two cartridges in the new handloading guide recently published by Western Powders. That source shows about the same velocity for a 160-grain bullet from the Remington and Weatherby cartridges, with both being about 200 fps slower than the 7mm STW. During our initial experiments with the 7mm STW, freeboring was tried, and while velocity could be increased, the idea was eventually abandoned when we were unable to consistently reach Jarrett’s accuracy requirement of three shots inside half an inch at 100 yards with a variety of bullet types and weights.

The question I have been asked most is which among the many hunts the 7mm STW and I have shared through the years is my favorite. Singling out one among many wonderful adventures is not easy, but twist my arm hard enough and the magnificent interior grizzly I bagged in the north country of Alaska with a single shot at 322 yards in 2010 will be at the top of the list. Federal had announced a Premium 7mm STW loading with the then-new 160-grain Trophy Bonded Tip (TBT) bullet, and my original plan was to use the ammo on the hunt. When it became apparent that it would not arrive in time, the company sent a supply of the first bullets made. I used the Jarrett 7mm STW No. 1 rifle on that hunt, and my handload consisted of the Federal case, Federal 215 primer, and the 160-grain TBT seated atop 79.0 grains of Reloder 25 for a velocity of 3,229 fps.

While the 7mm STW has more competition today than it did back in 1988, it continues to hold its own in the field with any cartridge of its caliber.