The .338 caliber is fast becoming the hot bullet size for long-range precision rifles-and for good reason. Match-grade bullets in that caliber, such as the 250-gr. Lapua Scenar and 250- and 300-gr. Sierra MatchKings, have higher ballistic coefficients than virtually any smaller-diameter projectile, and thus have flatter trajectories and are less subject to wind deflection. Interest in the .338 is largely the result of the success of the .338 Lapua Magnum. Its ballistics are indeed impressive-a nominal 2960 f.p.s. muzzle velocity, and nearly 5,000 ft.-lbs. of muzzle energy, with 250-gr. bullets. Yet the performance gap between the .338 Lapua and the venerable .50 BMG is still wide.

In 2008, Xtreme Machining of Grassflat, Pa., introduced a novel .338 cartridge and rifle to narrow that gap. The new round, christened the .338 Xtreme, was the result of a developmental collaboration between Xtreme Machining proprietor and master machinist Bob Zelenky, and ballistic experimenter Olan London. Both men were highly experienced 1,000-yard benchrest and .50-cal. competitors, and Zelenky had been producing precision actions, stocks and rifle accessories for years, so they were well-qualified to embark on such an ambitious project.

The .338 Xtreme cartridge is based on the huge .505 Gibbs case necked down, strengthened and given a sharper 35-degree shoulder. Full-case capacity of the .338 Xtreme is 161 grs. of water. But the new round is much more than an oversized .338 Lapua. Maximizing the performance potential of the large case is a new bullet, a 266-gr. lathe-turned tellurium-copper alloy projectile with a boattail shape that confers a ballistic coefficient of 0.825-significantly higher than that of any other .338-inch-diameter production bullet. This bullet has a unique, patent-pending, two-diameter design with a forward bearing portion measuring 0.331 inches, or about 0.001-inch more than land diameter, and a short driving band just forward of the boattail that opens up to 0.338 inches, and thus completely fills the grooves. The unique design reduces bore friction and chamber pressure, increases velocity, and gives enhanced accuracy as a result of better initial bullet alignment with the bore.

Brass for the .338 Xtreme is produced by Bertram Bullets of Australia, and loaded cartridges are produced by International Cartridge Corp. of Reynoldsville, Pa. Standard chamber pressure for factory ammunition is 61,100 p.s.i., producing a nominal 3350 f.p.s. muzzle velocity out of 30-inch barrels.

A new, oversized rifle action was necessary, with a 1.600-inch-diameter receiver of 420 stainless steel and a two-lug bolt of 4140 steel for a 0.800-inch body. Also needed was an oversized barrel measuring 1.400 inches at the receiver ring for maximum strength and hardness. Zelenky bores, rifles and heat-treats his own tubes from 416 stainless steel. Rifling is in a six-groove, 1:10-inch, right-hand twist, with six longitudinal flutes and a choice of 26- or 30-inch lengths.

Although the absolute chamber pressure for the .338 Xtreme is no greater than that of other modern high-performance rounds, the size of the case increases the area of the chamber walls on which this pressure can act. Since steel's tensile strength increases with hardness, Zelenky elected to harden all critical components to a higher level than is usually found: 44-46 Rc for the receiver and bolt, and 35-37 Rc for the barrel.

Features of the Xtreme Tactical's action include a 4.49-inch-long ejection port, a pivoting bolt release mounted on the left side, and pinned 0.250-inch-thick recoil lug. Each Xtreme Tactical rifle receiver is topped with a 40-minute Picatinny scope rail for long-range shooting. The bolt head is fairly conventional, but immensely strong, with two massive lugs, a spring-loaded plunger ejector, and a Sako-style extractor. Rifle Basix triggers with a pull weight of about 3 lbs., 4 ozs. are standard.

Stock options for the rifle include the A-5 tactical unit from McMillan Fiberglass Stocks using Xtreme Machining's own bottom metal, and the modular aluminum unit from McRee's Precision. The latter is designed to allow easy attachment of a host of tactical accessories, including night vision adapters, and is also available in a folding version that reduces total gun length (with a 26-inch barrel) to about one meter (39 inches). Additionally, single-shot target models can be ordered with a laminated-wood benchrest-style stock. With all stocks, the Xtreme Tactical's barrels are fully free-floated.

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