Broadhead-tipped arrows deliver a cutting impact that kills through hemorrhage, not blunt force or hydrostatic shock. Unlike rifle bullets, which travel fast enough to create a shockwave and cavitation through tissue, an arrow lacks the velocity for any of that. Instead, the broadhead works like a flying razor blade, slicing through blood vessels, organs, and tissue along a narrow wound tract. Death results from rapid blood loss and circulatory collapse.
Cutting Impact, Not Crushing Force
The distinction matters because it changes everything about how the projectile works on tissue. A high-velocity rifle bullet creates a temporary cavity far larger than the bullet itself, sending a pressure wave radiating outward from the wound channel. That cavitation effect can damage organs and tissue well beyond the bullet’s direct path. The subatmospheric pressure created by a bullet’s passage is powerful enough to suck hair fibers into the wound tract.
A broadhead arrow does none of this. It simply doesn’t move fast enough. Tissue damage is confined entirely to the immediate area the blades physically contact. There is no radiating shockwave, no temporary cavity, no energy dump into surrounding tissue. The wound channel is essentially the width of the broadhead’s cutting diameter and nothing more. This is why blade sharpness and shot placement are so critical in bowhunting: the broadhead has to directly cut something vital to be effective.
How Hemorrhage Causes Death
When a razor-sharp broadhead passes through the central chest cavity, it can sever the aorta, major arteries, large veins, or the heart itself. Any of these injuries causes an immediate or near-immediate drop in arterial blood pressure to the brain. According to Dr. Bengt Georén, a physician writing for the European Bowhunting Federation, a central lung hit that severs the aorta or other large thoracic arteries causes brain oxygen levels to drop within roughly five seconds, leading to rapid unconsciousness.
Even when the broadhead doesn’t hit the largest vessels directly, cutting smaller arteries and veins in the lung area drains returning blood volume from the heart. As bleeding continues, hypovolemic shock sets in once about 35% of total blood volume is lost. Heart rate spikes, blood pressure plummets, and when mean arterial pressure drops below 40 mmHg, the brain begins to fail. Below 30 mmHg, brain damage becomes irreversible, followed by unconsciousness and death.
A broadhead that passes through both lungs creates an additional lethal mechanism: bilateral pneumothorax, or double lung collapse. Even if the arrow misses the heart and major vessels entirely, collapsing both lungs blocks blood from circulating through the pulmonary system. Oxygenated blood can no longer reach the left side of the heart for distribution to the body. This condition is always fatal, typically causing unconsciousness within 30 seconds to four minutes.
Why Blade Sharpness Changes Everything
Because the broadhead relies entirely on cutting rather than energy transfer, sharpness directly controls how fast an animal bleeds out. A dull broadhead still creates trauma if it passes through vital organs, but it triggers a stronger clotting response. Damaged tissue releases more of the proteins that initiate blood clotting compared to a clean, razor-sharp cut. The result: a dull blade may kill, but the animal bleeds more slowly, travels farther, and takes longer to expire.
A razor-sharp broadhead produces faster blood loss in a shorter window. This reduces survival time and the distance an animal can cover after the shot. Sharp blades also increase the chances of a clean exit wound, which matters for tracking. A deer needs to lose roughly a third of its blood volume to enter shock or die, and a low exit wound created by sharp blades lets blood drain externally rather than pooling invisibly inside the body cavity.
Wound Channel Size by Broadhead Design
Fixed-blade broadheads and mechanical (expandable) broadheads create meaningfully different wound channels. Fixed blades have a narrower cutting diameter, typically between one and one-and-a-quarter inches. They introduce less resistance on impact, which helps with penetration, especially on larger or tougher animals. Their simplicity also means there are no moving parts to fail on contact with bone or heavy tissue.
Mechanical broadheads deploy their blades on impact, opening to cutting diameters that would be aerodynamically impossible with a fixed design. Some models cut channels of two inches or wider. This creates a substantially larger wound tract, faster blood loss, and a more visible blood trail for tracking. The tradeoff is that mechanical blades consume kinetic energy during deployment, which can reduce penetration depth, particularly on quartering shots or when the arrow contacts bone.
What Happens When Broadheads Hit Bone
Broadheads interact with bone very differently depending on bone type. Flat bones like ribs and shoulder blades can be perforated or fractured by a broadhead, allowing the arrow to continue into the chest cavity. The blades may crack or split the bone on the way through. Spinal columns also show significant damage from broadhead impacts, with the potential for the arrow to sever the spinal cord if it strikes the right angle.
Dense, thick bones like the femur tell a different story. An arrow striking a femur tends to embed deeply in the bone itself rather than passing through. The arrow essentially gets stuck, making extraction difficult and stopping penetration into tissue beyond the bone. This is one reason shot angle matters so much in bowhunting: a broadhead that has to pass through a heavy leg bone or the ball joint of a shoulder may never reach the vitals.
Momentum Versus Kinetic Energy
Because broadheads kill through cutting and penetration rather than energy transfer, the physics that matter are different from firearms. In the bowhunting world, momentum is a more useful predictor of penetration than kinetic energy. Kinetic energy measures what a projectile can do while moving through a medium, and it matters for bullets because that energy creates hydrostatic shock. At arrow speeds, there is no hydrostatic shock to generate, so kinetic energy becomes less relevant.
Momentum measures how much force is required to stop a moving object. A heavier arrow traveling at a slower speed can carry more momentum than a lighter, faster arrow with higher kinetic energy. Consider two arrows: a 475-grain arrow at 280 feet per second has more kinetic energy, but a 707-grain arrow at 230 feet per second has more momentum. When that heavier arrow encounters resistance from tissue, bone, or hide, it takes more force to stop it. The practical result is deeper penetration and a higher likelihood of a complete pass-through, which creates both an entry and exit wound for maximum blood loss.
This is why many experienced bowhunters prioritize total arrow weight and momentum over raw speed. A pass-through shot with two open wound channels bleeds faster and leaves a better tracking trail than an arrow that stays lodged in the animal, regardless of how much energy it carried on impact.