The .300 Winchester Magnum
By Chuck Hawks
The .300 Win. Mag. is the most successful and popular of the Big .30's, and the only one among the 10 best selling rifle cartridges. While most of the .300 Magnums are ballistically similar, far more factory loads are available for the Winchester version, and only the .300 Win. Mag. is available in such a wide variety of rifles. For the hunter who yearns to own a .300 Magnum for a standard length action, Winchester's Big .30 is the odds-on choice.
Winchester factory loads for the .300 Winchester Magnum give a 150 grain Power Point bullet a MV of 3290 fps and ME of 3605 ft. lbs. At 200 yards the figures are 2636 fps and 2314 ft. lbs.
A 165 grain bullet is probably a better choice for the .300 Win. Mag., given the powder capacity of the case and the superior sectional density (SD) of the heavier bullet. Winchester's factory load gives a 165 grain Fail Safe bullet a MV of 3120 fps and ME of 3567 ft. lbs. At 200 yards the figures are 2515 fps and 2319 ft. lbs. The trajectory of a 165 grain spitzer bullet at a MV of 3120 fps should look about like this: +3" at 100 yards, +3.4" at 200 yards, -1.2" at 300 yards, and -11.4" at 400 yards.
180 grains is the most popular bullet weight for all of the .300 Mags. Winchester loads their 180 grain Power Point Plus bullet to a MV of 3070 fps. and ME of 3,768 ft. lbs. At 200 yards the velocity is 2633 fps and the remaining energy is 2361 ft. lbs.
Winchester trajectory tables show that the 180 grain Power Point Plus bullet zeroed at 200 yards rises only 1.4" at 100 yards and falls 6.4" at 300 yards. This is identical to the trajectory for the 130 grain Power Point Plus bullet in the famous .270 Winchester caliber. Obviously, Winchester's .300 is a fine long range big game cartridge.
The flip side of launching heavy bullets at high velocity is recoil, and abundant recoil is the dark side of all .300 Magnum cartridges. You can't cheat Mother Nature or the laws of physics.
That said, 180 grain bullets remain the most popular choice among .300 Winchester Magnum reloaders, and with good reason. They are the most useful and versatile bullets for use in any .300 Magnum cartridge. Bullets heavier than 200 grains are not recommended for the .300 Win. Mag. due to its short neck.
The slower burning rifle powders are a natural choice for the .300 Win. Mag. H4350, IMR 4350 and RL-22 are good powders for 150-165 grain bullets. For the heavier 180-200 grain bullets H1000, H4831, IMR 4831, IMR 7828, RL-22, and RL-25 are among the recommended powders.
Here are some .300 Win. Mag. specifications of interest to reloaders: bullet diameter .308", maximum COL 3.34", maximum case length 2.62", MAP 54,000 cup.
According to the 26th edition of the Hodgdon Data Manual reloaders can drive a 165 grain bullet to a MV of 3031 fps with 79.0 grains of H1000 powder, and at a MV of 3207 fps with 84.0 grains of H1000. These velocities were also achieved in a 26" test barrel.
Also according to the Hodgdon Data Manual, reloaders can drive a 180 grain bullet to a MV of 2945 fps with 78.0 grains of H1000 powder, and to a MV of 3121 fps with 83.0 grains of H1000. The latter load developed a pressure of 50,900 cup. These Hodgdon loads used Large Rifle Magnum primers and were chronographed in a 26" pressure test barrel.
Note: A full length article about the .300 Winchester Magnum can be found on the Rifle Cartridge Page.
Copyright 2004, 2016 by Chuck Hawks. All rights reserved.