The Weatherby 25 WBY RPM 107gr Hammer Custom load is a box of 20 rounds of 25 Weatherby RPM hunting ammunition built on premium brass (Weatherby part no. M25RPM107HCB). The 25 Weatherby RPM follows the design philosophy of the 6.5 and 338 RPM cartridges: a rebated precision magnum case that fits a lighter, more compact rifle without giving up velocity or downrange capability. Hammer Custom bullets are turned on a CNC lathe from a solid copper blend, each one weighed and micrometer measured, with a hollow-point design that sheds petals immediately while the rest of the bullet stays intact. Weatherby publishes a muzzle velocity of 3,350 fps and 2,666 ft-lbs of muzzle energy for this 107-grain load, still carrying 2,409 fps at 500 yards. Weatherby lists a 2026 production start for the cartridge.

Key Specifications

• The cartridge is 25 Weatherby RPM, a rebated precision magnum in 25 caliber built for the lightweight Mark V 6-Lug action.
• Bullet weight is 107 grains, the load weight Weatherby lists for this part number.
• The bullet is the Hammer Custom, and every bullet is weighed and measured for consistency.
• The G1 ballistic coefficient is .510, a measure of how well the bullet resists drag as it flies.
• Muzzle velocity is 3,350 fps from Weatherby published ballistics, which sets the flatness of the trajectory.
• Muzzle energy is 2,666 ft-lbs, the starting point for the energy the bullet delivers downrange.
• Box quantity is 20 rounds, a standard count for sighting in and a hunting trip.

Frequently Asked Questions

What bullet does this 25 WBY RPM load use? It uses a 107-grain Hammer Custom. Hammer Custom bullets are turned on a CNC lathe from a solid copper blend, each one weighed and micrometer measured, with a hollow-point design that sheds petals immediately while the rest of the bullet stays intact.

What velocity and energy does this load publish? Weatherby lists 3,350 fps and 2,666 ft-lbs at the muzzle, falling to 2,948 fps and 2,064 ft-lbs at 200 yards and 2,409 fps and 1,378 ft-lbs at 500 yards.

What is the 25 WBY RPM cartridge? The 25 Weatherby RPM follows the design philosophy of the 6.5 and 338 RPM cartridges: a rebated precision magnum case that fits a lighter, more compact rifle without giving up velocity or downrange capability. Weatherby lists a 2026 production start for the cartridge.

Buy the Weatherby 25 WBY RPM 107gr Hammer Custom Rifle Ammunition, 20-Round Box

Weatherby builds this 25 WBY RPM load around a 107-grain Hammer Custom so the cartridge performs the way its design intends. Order it from Weatherby‘s selection of rifle ammunition through our Lubbock, Texas gun shop for fast, insured shipping.