The 7mm STE

Down through the decades, a number of wildcat cartridges have been created for lever-action rifles, and many have been around for a long time. Fred Wade came up with the .30 Lever Power and .35 Lever Power--formed from shortened .30-40 Krag cases--for the Winchester 94 and Marlin 336 rifles in the 1950s. Also on the .30-40 Krag case--and of about the same vintage--was the .44 Van Houten Super, which no doubt inspired the introduction of its performance twin in 1964: the .444 Marlin.

One of the more famous lever-action wildcats is the .450 Alaskan. Developed specifically for the Winchester Model 71 by gunsmith Harold Johnson, it is based on the .348 Winchester case and was once popular among brown bear guides. Today, the .450 Marlin cartridge provides similar performance.

My contribution to the lever-action wildcat story is the 7mm Shooting Times Easterner, which is based on the .307 Winchester case. Not long after Winchester introduced the .307 in 1982, it dawned of me that it begged to be necked on down to 7mm, but I put the idea on the back burner due to a lack of flat-nosed 7mm bullets--which of course are necessary for safe use in the tubular magazines of Winchester 94 and Marlin 336 rifles.

Later, my interest in the project was renewed by the introduction of a Nosler 120-grain 7mm flatnose bullet, and when Hornady introduced a 139-grain flat-nose I decided to go ahead with it. Icing was added to the cake with the later introduction of a 130-grain flatnose by Speer.

In 1987 I had Harry McGowen rebarrel a Marlin 336 with a 22-inch, straight-taper barrel with a muzzle diameter of .640 inch and a rifling twist rate of 1:10. The barrel was chambered for the .307 Winchester case, necked down to 7mm.

Initially I experienced sticky case extraction long before reaching the velocities I had anticipated, so I opened up the chamber with a reamer I had developed for another wildcat that had minimum body taper and a 40-degree shoulder angle. Problem solved.

By simply changing the shape of the case I was able to increase velocity by 300 fps before experiencing sticky extraction. To be on the safe side, I then dropped back 100 fps below that level of pressure, arriving at maximum velocities of 2,900 fps for the 120-grain bullet and 2,700 fps for the 139-grain bullet.

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As a way of standardizing chamber dimensions for the 7mm STE I sent formed cases to JGS Precision Tool Manufactring (541-267-4331) and had them grind chamber reamers for it. I also sent fired cases to RCBS and Redding for reloading dies.

The case is formed by necking down the .307 Winchester case and then using a reduced load--I usually use 40.0 grains of H414 behind the 120- or 139-grain bullet--to fire-form it to a 7mm STE chamber.

Once a batch of cases has been fire-formed, it is ready for full-power loads. Powders of medium-slow burn rate are the best choices, namely Reloder 19, IMR-4350, H4350, H414 and W760. Although I have not tried them in this cartridge, other powders with similar burn rates such as Accurate 4350, VihtaVuori N550 and Norma 204 should also be excellent choices.

Due to the necessity of loading flat-nose bullets in tubular magazines, bullet options for the 7mm STE have always been rather limited, and the latest news is not exactly bright. The Nosler 120-grain flat-nose bullet is no longer offered to handloaders, and while Hornady still has 139-grain bullets in stock, no more will be made once the supply is exhausted.

7MM STE HANDLOADS

BULLET BULLET WEIGHT (gr.) POWDER CHARGE WEIGHT (gr.) NUZZLE VELOCITY (fps) Nosler FN 120 RL-19 50.0 2,807 Nosler FN 120 IMR-4350 48.0 2,894 Nosler FN 120 W760 47.0 2,910 Nosler FN 120 H414 47.0 2,916 Nosler FN 120 H4350 49.0 2,873 Speer FN 130 RL-22 51.0 2,752 Speer FN 130 RL-19 49.0 2,833 Speer FN 130 IMR-4350 47.0 2,761 Speer FN 130 RL-19 49.0 2,833 Speer FN 130 IMR-4350 47.0 2,761 Speer FN 130 H414 46.0 2,810 Hornady FN 139 IMR-4350 46.5 2,704 Hornady FN 139 W760 45.0 2,677 Hornady FN 139 H414 46.5 2,704 WARNING:All powder charges are maximum and should be reduced by 10 percent for starting loads. Cases formed from .307 Winchester brass; Winchester WLR primers were used. Velocities shown are averages of five or more rounds clocked 12 feet from the muzzle of a 22-inch barrel.

That leaves the Speer 130-grain flat-nose as the only sure option. Luckily, it's plenty accurate in my rifle. It's also heavy enough to use on any game for which the 7mm STE is suited. Word to the wise here: If you own a rifle in 7mm STE, it would be smart to stock up on bullets while you can.

The 7mm STE is no slouch out to 300 yards or so. When zeroed three inches high at 100 yards it drops about seven inches low at 300, where it delivers between 800 and 950 ft.-lbs. of energy, depending on bullet weight.

It's funny how some things sometimes work out. While I had eastern whitetail hunting in mind when designing the 7mm STE, the first game I took with it was a mule deer at 260 yards.