The idea behind using heavy-for-caliber bullets is might makes right. Say you shoot a 175-grain bullet instead of a 140-grain bullet in your 7mm magnum, or a bullet weighing 180 or 200 grains instead of 150 grains in your .30/06. You’ll do better on big game for the following three reasons.
1 – Lower Cost**
A bullet with a plain copper-alloy jacket and lead core performs fine on big game if it weighs enough and strikes game at a moderate velocity–2,600 feet per second (fps) or so. One such bullet is Hornady’s tried-and-true InterLock, which costs about $30 for a box of 100 bullets–about a third the cost of Hornady’s premium gilding-metal-constructed GMX bullets.
2 – Excellent Penetration**
A lead-core 150-grain bullet fired at 3,300 fps from a .300 magnum might tear into pieces when it hits game. But adding some weight and decreasing velocity by 300 to 400 fps will help it remain intact to penetrate. Lighter bullets at higher speeds do shoot flatter, but the difference amounts to only about 4 inches at 400 yards.
In addition, heavier bullets carry more momentum than faster, lighter bullets. That difference in momentum grows as distance increases. The result is deeper penetration, and penetration and adequate bullet expansion are what kill game. A few years ago I fired a 250-grain bullet from a .35 Whelen at a bull elk. The bullet punched clear through the bull, which rolled over dead, even though the bullet packed only 1,800 foot-pounds of energy, about the same as a 100-grain bullet from a .243 Win.
#3 – More Meat
Because heavy bullets at moderate velocity expand less violently, they cause less bloodshot meat. I used to shoot 150-grain bullets from my .30/06 to kill antelope. Those light bullets ruined quite a lot of shoulder meat, even though they went through the lungs. I finally switched to 180-grain bullets. The heavier bullets travel 300 fps slower and poke a neat hole through the antelope without damaging a bite of meat.
From the May issue of Outdoor Life magazine.