Compared: The .243 Winchester and 6mm Remington
By Chuck Hawks
Two cartridges with similar performance are the .243 Winchester and the 6mm Remington, and both use .243 inch bullets. The .243 Winchester is based on a necked down .308 Winchester case, and the 6mm Remington is based on a necked down .257 Roberts case. Both of these .24's are better varmint cartridges than the .25's, while remaining adequate for deer and antelope. Each is covered in detail in articles on the Rifle Cartridge Page.
Generally, in .24 caliber, the 55 to 80 grain bullets are the varmint bullets; the 90 to 115 grain bullets are designed for larger game, and the 85-87 grain bullets can be either (but not both). For comparison with other calibers, the Speer 80 grain spitzer has a ballistic coefficient (BC) of .365 and a sectional density (SD) of .194; the Speer 100 grain big game spitzer bullet has a BC of .351, and a SD of .242.
The .243 Win. and 6mm Rem. will cycle through almost any short action rifle. These .24 caliber cartridges have become the favorites of hunters who want to shoot varmints, predators, and deer size game with the same rifle. Recoil energy is low and trajectory is flat, both of which contribute to the .24's reputation for deadly practical accuracy.
The .243 Winchester is one of the most successful rifle cartridges introduced since the end of the Second World War. Winchester introduced it in 1955 on a necked-down version of the .308 Win. case and it almost immediately became a best seller. Today just about every ammunition manufacturer produces .243 factory loads, and almost every rifle manufacturer with an action strong enough to handle its 52,000 cup maximum average pressure (MAP) chambers for it. The selection of rifles in .243 is huge.
The .243 Win. is the sixth best selling CF rifle cartridge in the U.S. on most sales charts. .243 ammunition can be bought just about anywhere in the world that ammunition is sold.
Typical .243 factory loads launch an 80 grain varmint bullet at a muzzle velocity (MV) of about 3350 fps. Typical .243 factory loads for medium size big game launch a 100 grain bullet at a MV of 2960 fps with muzzle energy (ME) of 1945 ft. lbs. Handloaders routinely duplicate these loads.
The 6mm Remington started life in 1955, the same year as the .243 Win. It was based on the .257 Roberts case, necked down and with a sharper shoulder, and was originally named the .244 Remington. It is also loaded to a MAP of 52,000 cup.
The .244/6mm had a troubled introduction and has never approached the popularity of the .243 Winchester. Still, it is factory loaded by all of the Big Three North American loading companies, although bullet selection in factory loads is limited. New factory made rifles are another matter. Only a few models are available in 6mm Remington caliber.
Factory loads in 6mm advertise an 80 grain varmint bullet at a MV of 3,470 fps and a 100 grain game bullet at a MV of 3,100 fps with ME of 2133 ft. lbs. The 6mm Remington is a flexible cartridge for which to develop loads, and reloaders can duplicate the factory velocities.
Clearly, since these two cartridges use the same bullets, frontal area and sectional density are identical. Whatever difference in killing power exists between the two cartridges will be determined by velocity (and hence energy).
Because the necked-down .257 case has a bit more powder capacity than the necked down .308 case, when both are loaded to maximum pressure with 100 grain bullets the 6mm has a 117 fps velocity advantage and a 118 ft. lb. energy advantage at 300 yards.
According to the "Maximum Optimal Ranges for Big Game" table, using 100 grain bullets on 200 pound game, the .243 Winchester has a maximum optimal range of 240 yards, compared to 295 yards for the 6mm Remington. This indicates the somewhat superior killing power of the 6mm Remington.
In trajectory the 6mm also has a modest advantage over the .243, again due to its higher velocity. If identical 100 grain bullets from typical factory loads are zeroed at 200 yards, the bullet from the .243 will drop 7.8 inches at 300 yards, while the 6mm bullet will drop only 7.0 inches (Winchester figures).
On the other hand, the .243 has a modest advantage in recoil. If typical 100 grain factory loads are fired in 8 pound rifles, the "Rifle Recoil Table" shows 8.4 ft. lbs. of recoil energy for the .243 Winchester and 10.0 ft. lbs. of recoil energy for the 6mm Remington.
I have experience with, and a fondness for, both of these calibers. They are versatile, accurate, and pleasant to shoot. It is hard to go wrong with either.
While the 6mm Remington has a modest ballistic advantage over the .243 and the .243 Winchester has a modest recoil advantage over the 6mm, the biggest difference between the two calibers is the .243's advantage in available factory loads and commercially manufactured rifles. In many places it is hard to find a rifle in 6mm Remington, while .243 rifles are common.
More than anything else, it is this advantage in available rifles that is likely to decide the .243 Win. Vs. 6mm Rem. comparison in favor of the .243. The differences in ballistics and recoil are less important than finding a suitable rifle at an affordable price.
Copyright 2003, 2012 by Chuck Hawks. All rights reserved.