The .243 Winchester is a better varmint cartridge than the .25’s, while remaining adequate for deer and antelope. The .243 launches an 80 grain varmint bullet at a muzzle velocity (MV) of about 3,350 fps. This means that it shoots about as flat as a .22-250, only its 80 grain spitzer bullet has a BC of .365, compared to the 55 grain .22 spitzer’s BC of .255. This is an enormous difference, and explains why the .24’s are so much better than the .22’s on windy days.
When using the .243 to hunt medium size big game animals, bullet selection is paramount. Rapid (but controlled) expansion is very important, as the small diameter 6mm bullet has little shocking power if it does not expand and expend its energy inside of the animal. Two bullets in the 90-100 grain weight range that have earned a good reputation on medium size big game animals are the Remington Core-Lokt and Nosler Partition.
Winchester’s Supreme 95 grain Ballistic Silvertip big game bullet is factory loaded to a MV of 3,100 fps with 2,021 ft. lbs. of muzzle energy (ME). If that load is zeroed to strike 2.5 inches high at 100 yards the bullet will then strike 3 inches high at 150 yards, 2.3 inches high at 200 yards, and 3 inches low at 300 yards. At 200 yards that bullet hits with 1,455 ft. lbs. of energy, and at 300 yards it still retains 1,225 ft. lbs. of energy. With this load so zeroed the .243 Winchester is about a 300 yard deer and antelope cartridge.
Reloaders with a .243 are in luck. There are bullets from 55-115 grains from which to choose, and many common powders are adaptable to the .243. Also, .243 brass is strong and plentiful. Generally, bullets from 70 to 80 grains are the best choice for varmint hunting, and bullets from 90 to 105 grains are the best choice for hunting CXP2 class game. Here are some important specifications for reloaders: bullet diameter .243″, maximum case length 2.045″, maximum COL 2.71″, MAP 52,000 cup.
Bullets lighter than 90 grains are generally varmint bullets, and bullets 90 grains and heavier are generally intended for big game hunting. The distinction is important because the internal construction of the two types of bullets is quite different. Very few bullets are adaptable to both purposes.
According to the Nosler Reloading Guide No.5 their 80 grain Ballistic Tip varmint bullet can be driven to a MV of 3041 fps with 38.5 grains of H380 powder and 3291 fps in front of 42.5 grains of H380.
My favorite general purpose .243 load uses a Hornady 87 grain BTHP bullet in front of a maximum load of 37.1 grains of IMR 4064 powder for a MV of 3100 fps. Hornady technicians developed this load in Hornady cases using Federal 210 primers. It provides very good accuracy in my Browning 1885 Low Wall rifle.
According to the Nosler Reloading Guide No.5 their The 95-100 grain big game bullets can be driven to a MV of 2909 fps with 37.5 grains of IMR 4350 powder, or 3060 fps in front of 41.5 grains of the same powder.
The technicians at Nosler used Winchester cases and Remington 9 1/2 primers for their load development. The Nosler loads were chronographed from a 24 inch barrel.
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