Your Rifle Makes Smaller Holes Than My Bow!

ARTICLE BY: Jared Miller

…if you impact below 2200 fps.

Hunters have been obsessed with energy for generations, and unfortunately they’re wrong. Energy doesn’t tell you much about the size of a wound channel, and thereby the speed at which an animal will bleed out. Impact velocity tells you far more about whether your bullet performs at all and what your wound channel is likely to look like.

2200 fps is the generally accepted impact velocity that can reliably cause hydraulic shock and extend the wound channel beyond just the tissue that comes into direct contact with the projectile. Case in point, my bow at 50 yards impacts with a measly 57 ft-lbs of energy, but my broadhead with a 1.75″ main blade plus the bleeder makes a bigger permanent wound channel than your 180 grain .300 Win. Mag. at 1800 fps impact velocity, even though you’re hitting with over 20 times the energy.

A distinction worth noting: hydraulic shock and hydrostatic shock get thrown around a lot and are often used interchangeably. Hydraulic shock is the expansion of the temporary wound channel beyond what comes into direct contact with the projectile — experts call this temporary cavitation. Hydrostatic shock is the theory that a pressure wave reaching the CNS renders an animal temporarily unconscious. Neither one kills an animal directly, but both can aid in recovery. Hydrostatic by dropping the animal in its tracks, giving the wound through the vitals time to cause blood loss and asphyxiation. Hydraulic by expanding the wound channel and speeding up that same process.

Worth knowing: the temporary wound channel does the most damage in dense, inelastic tissue like liver and kidneys. Lung and muscle are elastic — they stretch and largely recover. So the mechanism matters most in exactly the place most of us aren’t aiming, meaning when we’re not perfect, it buys us some forgiveness.

Let’s see why this matters. Here are three of the most popular loads for the .300 Win Mag, at 6000 feet elevation and 40 degrees temperature.

*Mind you these numbers are based on factory stated muzzle velocities and are likely best case scenarios.

Whether you use a minimum impact velocity of around 1800 fps, which is a number that gets thrown around as the minimum for most bullets to reliably expand, or a minimum of 1500 ft-lbs of energy for an elk (again a number that’s been floated around for decades), both of those rules put you well beyond the distance at which your bullet drops below the 2200 fps threshold needed for hydraulic shock.

Here’s what I’m actually cautioning you on. Know your rifle’s impact velocity at the distance you’re shooting, and know whether you can keep eyes on the critter and whether you’re close to a property boundary. Hydraulic shock makes the kill happen more efficiently, but it isn’t necessary if you can watch the animal for as long as it’s on its feet.

A hole through the vitals will kill. But it doesn’t do you any good if it’s a pencil-sized wound that doesn’t leave a blood trail and the animal makes it 500 yards onto the neighbor’s place who won’t let you recover it. Same goes for last light. A long tracking job at 5:40 p.m. in October is a different problem than the same one at noon.

None of this means you can’t shoot past 400 yards. The bowhunter knows there is zero possibility of hydraulic shock and the hole he makes through a critter will never be any bigger than what comes into direct contact with the broadhead, but he knows that going in. Your bullet has far more variables as to the possible size of the hole it can make in a critter. The key point here; know your weapon, know how your bullet performs at varying impact velocities, and take that into account given your hunting location, time of day and situation.