Bullet Penetration On Big Game

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Hunters of big animals, such as elk, moose and bears, have long been instructed to shoot the heaviest bullets available in their cartridges. The benefit is deeper penetration. Or should we say “was” better penetration? The truth is many of today’s lighter controlled expansion bullets penetrate better than heavier traditional cup-and-core bullets of yesteryear.

The problem with cup-and-core lead-nose slugs is erosion of the lead. It can break into small pieces, which hinders penetration, but even if it stays in one piece, much of the soft lead is wiped away against hide, muscle and bone. As weight falls away, penetration decreases.

Lead can be hardened (add tin to the alloy) to reduce erosion loss. It can also be bonded (welded) to a thicker jacket or locked inside a partition within the shank to minimize loss of mass. Nosler Partition and Swift A-Frames work this way, retain 60- to 80 percent of their weight, and penetrate much deeper than cup-and-core bullets.

Spomer's Bullet Penetration On Big Game 3-14 BULLET FRAGMENTS 2
Old-style cup-and-core bullets can deform, break apart or mushroom excessively, hampering penetration. The expanded monolithic hollow point Barnes TSX on the right dramatizes how modern bullets of this type retain 90- to 100 percent weight for consistent expansion
and extremely deep penetration.

Another option is to make bullets of one material, usually copper or copper alloy. Examples of these bullets include Remington Copper Solid; Barnes TSX, TTSX and LRX; Nosler E-Tip; Winchester Power Core 95/5; and Hornady GMX. A hollow is punched into the nose. When wet tissue enters this, hydraulic pressure forces the copper nose to expand, but at the base of the hollow this expansion stops. Since there is no lead to erode and the copper is tough and durable, weight retention is often 90 percent or more. I recovered a 180-grain .308 bullet from a snowbank behind a dead grizzly it had passed through. The expanded bullet weighed 180 grains!

A few seasons back I fired a .270 WSM Browning A-Bolt rifle to drive a puny little 130-grain Winchester XP3 bullet through both shoulders of a big bull moose trotting 220 yards away. That “light” bullet landed somewhere back in the tundra. The moose landed on his nose after a 30-yard dash. Not bad for a bullet the guide had warned me was too light.

The rules have changed. Hunters using monolithic bullets can now shoot lighter weights to get equal or better expansion and penetration than the old heavyweights. Recoil will be less, trajectories will be flatter — and the game should be flatter, too.

Make sure you visit Sportsman’s Guide for a full assortment of rifle ammo.

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