Spomer on Shooting: Match Bullet to Velocity

When considering bullets for various kinds of game, hunters should consider muzzle velocity as well as intended target to maximize effective results.

As a general rule, one should choose heavier and harder bullets when taking on larger animals to ensure adequate penetration and impact energy. In a .270 Win., for instance, one would shoot a 130-grain soft-point, Core-Lokt, Power Point, SST, Ballistic Tip, etc., for pronghorns and whitetails, a 150-grain Partition, A-Frame, TTSX, Interbond, Power Core, Bear Claw etc., for elk and moose.

The same bullet, even the premium, controlled expansion types, mushroom differently depending on impact velocity/energy.
The same bullet, even the premium, controlled expansion types, mushroom differently depending on impact velocity/energy.

That said, modifications can and should be made if muzzle velocities — and especially anticipated impact velocities — are higher or lower. Sticking with the .270 Win. for now, there is a lot more impact energy and bullet trauma at 50 yards or 100 yards than 250- or 300 yards. At 100 yards, a typical 130-grain, .270 bullet is still zipping along at 2,800 fps or so and carrying 2,320 foot pounds (f-p) of energy. That can make frangible bullets break into pieces or flatten like pancakes against major bone and muscle. At 300 yards that same bullet will have slowed to 2,400 fps and be landing with just 1,695 f-p of kinetic energy. It could mushroom minimally, retain more mass and penetrate farther.

Obviously, at ever farther distances, these decreases in speed and energy minimize expansion even more. Eventually, depending on bullet construction, expansion stops and terminal bullet performance mimics a solid.

So now the big conundrum: do you choose a fairly hard bullet for an anticipated close range shot at high velocity or a soft one in case you need to engage at long range?

Jacketed cup-and-core bullets (Left) can shed parts. Bonded core bullets (2nd from Left) can mushroom as much and lose lead to scouring, but core and jacket can't part company. Partition types (3rd from left) expand at the nose, but shanks remain intact within the rear jacket compartment. Monolithic bullets expand when hydrodynamic pressures in the nose cavity force petals to peel back. Expansion stops at the base of the hollow cavity and the bullet usually stays in one piece to penetrate deeply.
Jacketed cup-and-core bullets (Left) can shed parts. Bonded core bullets (2nd from Left) can mushroom as much and lose lead to scouring, but core and jacket can’t part company. Partition types (3rd from left) expand at the nose, but shanks remain intact within the rear jacket compartment. Monolithic bullets expand when hydrodynamic pressures in the nose cavity force petals to peel back. Expansion stops at the base of the hollow cavity and the bullet usually stays in one piece to penetrate deeply.

Part of your answer can be found in initial muzzle velocity. A .30 Remington AR cartridge throwing a 150-grain, .308 bullet at 2,575 fps is a lot slower than a .300 RUM throwing the same bullet 3,500 fps! Unless you reserve all shots for 400 yards or farther, you’ll want a pretty hard, controlled expansion bullet in this big magnum cartridge.

Reverse that thinking for the relatively slow .30 Rem. AR. At 300 yards its 150-grain bullet will have slowed to just 1,812 fps and be packing just 1,080 f-p of energy, borderline for expansion with many bullets.

Various bullet-makers have addressed this challenge with hybrid bullets, such as the Nosler Partition, which combines a traditional soft lead nose with a locked in lead shank. The Barnes TTSX is engineered to peel open quickly with as little as 1,600 fps impact velocity while keeping its solid copper shank in one piece, driving forward. Various bonded core bullets expand quickly thanks to soft lead cores, but keep jacket and core together by joining them via welding.

There is no perfect answer for this perennial terminal-performance challenge, so you’ll have to keep your eyes open, pay attention, observe what happens with your bullet at various impact distances, and modify your choices as you learn.

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