The fine .257 Roberts is based on a necked-down 7mm Mauser case, and was legitimized by Remington in 1934. From then until the introduction of the hot .243 Winchester and .244/6mm Remington in 1955, the .257 was the top selling combination varmint/deer cartridge.

The .257 is offered in a number of factory loads with 117-120 grain bullets. The 120 grain spitzer bullet as factory loaded by Federal claims a muzzle velocity (MV) of 2,780 fps and muzzle energy (ME) of 2,060 ft. lbs. At 200 yards the velocity is 2,360 fps and the energy is 1,480 ft. lbs.

Hornady offers a factory load in their Light Magnum line that drives a 117 grain spire point bullet at a MV of 2,940 fps and muzzle energy (ME) of 2,245 ft. lbs. At 200 yards the velocity is 2,460 fps and the energy is 1,572 ft. lbs. The trajectory of that load should look about like this: +2.6" at 100 yards, +2.1" at 200 yards, -3.9" at 300 yards. The maximum point blank range (+/- 3") is 289 yards. This Hornady load is listed as a "+P" load.

Here are some specifications of interest to reloaders: bullet diameter .257", maximum COL 2.780", maximum case length 2.233", MAP 45,000 cup (50,000 cup +P).

Because most factory loads for the .257 Roberts are loaded light, the reloader with a strong .257 rifle can do very well, indeed. Note that commercial +P cases have thicker walls than standard pressure .257 cases. The following loads were developed in +P cases and the maximum loads are +P loads. Reduce maximum loads by 2 grains for standard cases or weak rifles.

The Speer Reloading Manual Number 13 lists the following loads. An 87 grain spitzer bullet in front of 47.0 grains of H4350 powder for a MV of 3161 fps, or a maximum charge of 51.0 grains of the same powder for a MV of 3381 fps.

A 100 grain Speer spitzer in front of 41.0 grains of W760 powder for a MV of 2804 fps, or a maximum load of 45.0 grains of W760 for a MV of 3113 fps.

The 120 grain Speer spitzer bullets with 41.0 grains of IMR 4831 powder for a MV of 2552 fps, or 45.0 grains of IMR 4831 behind the same bullet for a MV of 2793 fps. Winchester cases and CCI primers were used for all of these loads, which were chronographed in a 24" barrel. Speer recommends the CCI 200 standard large rifle with H4350 and IMR 4831 powders, and the CCI 250 magnum primer with W760 powder.

Note: A full length article about the .257 Roberts can be found on the Rifle Cartridge Page.