How Important is Arrow Speed in Bowhunting?

For some bowhunters, September ushers in the first opening day of the year. For others, the start of bow season is still a few weeks away. Regardless of which camp you’re in, this is likely true: There are still a few last-minute tasks to attend to before things get really serious.

I admit to fully being in that boat. No matter how much I plan, I seem to be always scrambling to finalize details as a new season begins.

There’s also another bit of truth to be had here. With archery seasons rolling, the impacts of momentum and kinetic energy are being felt in game across the nation.

I shoot a few arrows a week throughout the summer, so any last-minute tuning task is usually pretty quick because I’m careful to ensure the arrows I practice with match the spine, weight and overall design of my hunting arrows minus the broadheads.

While I don’t get into the ultra-heavy arrow game, I use a moderately heavy hunting arrow with a broadhead weighing 125 grains and an additional 25-grain collar behind it. This added weight costs me a bit in raw speed downrange, but the advantage is increased kinetic energy and momentum.

SPEED VS. GREED

There was once a time when arrow speed was the most talked-about aspect of a bowhunter’s setup. Thankfully, those days are behind us as more and more bowhunters are learning about the benefits of heavier arrow setups for hunting. Honestly, I never understood the speed craze.

With few exceptions, bows that delivered blazing speeds were loud and hard to shoot, and the arrows capable of delivering those top speeds were mostly wispy and less durable than stouter, heavier shafts.

As a bowhunter, I’m shooting arrows with a singular purpose: to kill a critter. My top goal is to deliver arrows with plenty of momentum accurately.

Momentum is the product of an object’s mass and velocity. In archery, momentum directly impacts an arrow’s penetrating power—the force with which it strikes its target and the depth to which it can penetrate through flesh and bone.

Kinetic energy (KE), on the other hand, represents the energy that an object possesses by its motion. To simplify, think of it this way: KE is the energy an arrow stores in flight, and momentum is the ability to maintain energy upon meeting resistance. For example, a passenger train moving 85 mph down a track has significant KE but less momentum compared to a cargo train loaded down with containers of steel and grain, even if that train is traveling at a slower rate of speed.

When it comes to bowhunting, high KE is good because it means your arrow has plenty of energy. But without sufficient momentum, that energy quickly erodes upon meeting resistance, such as the shoulder bone of a whitetail.

Increasing arrow speed increases KE. It also increases momentum. However, there is a fine line to walk. Increasing speed usually requires a reduction in arrow weight. This will likely increase KE at a faster rate than momentum. A simple Google search will put you on several online KE and momentum calculators. I’d suggest you use one and see how your setup compares. If you’re shooting a 100-grain broadhead, consider upgrading to a heavier head. Calculate the difference in momentum, and you might be surprised by the results.

Let’s look at a real-world example. A 450-grain arrow traveling at 280 fps delivers 78.26 foot-pounds of KE and .559 slugs of momentum. Increase that arrow speed to 310 fps by reducing the arrow weight to 370 grains, and you’ll have upped KE to 78.88 foot-pounds but reduced momentum to .509 slugs.

Finding the optimal combination of speed, weight and momentum involves a balancing act. It’s also important to consider the terrain and species you hunt and your personal hunting style.

For whitetails, the minimum required amount of KE is generally accepted to be about 40 foot-pounds. Most bows above 55 pounds of draw weight will have no problem generating that number. Lower-poundage bows, however, are generally delivering slower arrows than higher-poundage models.

I’m not an especially good shot with a bow at long ranges, and the areas I hunt typically aren’t ideal for long-range shots anyway. Thus, I’m not terribly worried about wind drift or arrow drop past 50 yards. I use a heavy arrow that delivers maximum momentum without going too far overboard. With the online calculators and the array of options for arrow shafts and broadheads, adjusting arrow weight is easy.

If you take longer shots or hunt more open country, you may see a real benefit from a flatter, faster arrow. But you have to keep momentum in mind.

It’s not too late to up the lethality of your hunting arrows. Adding a heavier broadhead or moving to a heavier arrow shaft can make a big difference. If your bow is tuned—and it should be at this point of the year—the time to get your heavier arrow setup dialed in should be minimal. The benefits, however, can be significant.

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