With so many carbon arrows to choose from for bowhunting, it’s a tough job, but here’s what you need to know.
It’s that time of year when serious bowhunters are getting their equipment tuned up and replenishing their gear—or at least they should be while prices and availability are in that happy spot. Carbon arrows, especially, get lots of attention now as archers consider past years’ performance and look forward to improving their odds for the upcoming season. Arrows are also likely to cause the greatest amount of confusion. Walk into a well-stocked archery pro shop or sporting goods store and your eyes likely glaze over from the massive choices in arrows. The default action for many is to go with whatever the in-store “expert” recommends, or to use price as the guide — rather than intended or needed performance.
That’s unfortunate, because while we all put great stock in our bows, bow accessories and broadhead choices, a diligent and deliberate approach to choosing carbon arrows is often lacking. Granted, the manufacturers don’t always make this an easy process with so many models and minor variations on a theme to choose from across so many different brands. That is why, for many bowhunters, arrow selection comes down to price, not performance.
So, what comprises the ultimate bowhunting shaft—the one that will deliver the absolute best overall performance, whether you’re chasing local whitetails or pursuing that once-in-a-lifetime trophy elk?
That question begs a more refined question — what is “performance?”
For carbon arrows, performance is a multi-legged monster because there are many variables involved, and each variable affects the other variables for better or worse. It’s all about balancing these variables and going into the process understanding that there is no free lunch. Get more of this, you lose some of that.
When we speak of performance in terms bowhunting shafts, we must consider several variables that influence our goal of making a quick, clean and ethical kill: shaft weight, shaft size, spine deflection and friction coefficient. In the end, all of these come together to give us the ultimate goal of a bowhunting arrow—penetration. Without good penetration, nothing else matters. Making things potentially more complicated in our discussion is the fact that some of these variables influence more than one arrow dynamic.
Take, for example, spine deflection. This refers to the stiffness of an arrow, and it manifests itself in how an arrow flies after leaving the bow. Arrows bend once the bowstring is released and they continue to flex until the material elasticity subsides and rotational forces straighten them out. The objective is to find an arrow spine, based on bow weight and the archer’s draw length, that exhibits just the right amount of bend to fly straight and ensure downrange accuracy. Furthermore, too much or too little spine deflection can cause erratic arrow flight and accuracy will suffer. Selecting the proper arrow spine and making any necessary adjustments with point weight and insert combinations, slight bow weight adjustment, and experimenting with vanes and nocks effectively removes spine deflection from our list of performance variables.
Now that we have well-tuned arrow flight thanks to proper spine selection, we need to ensure that we deliver the maximum amount of energy to our target for optimal penetration. This is what we call kinetic energy, and it is influenced by an arrow’s weight and the speed at which the arrow is moving when it hits the target. This is where the big balancing act comes into play, and where the debate has raged the loudest in bowhunting circles—which is best for arrow penetration: arrow weight or arrow speed?
The simple answer is both. The more complicated answer is that it depends.
For most whitetail hunting setups with shots averaging 14 to 20 yards, arrow speed is not as crucial as it is for Western bowhunters often faced with 40-, 50- or even 60-yard shots on mule deer or antelope. We’re talking about speed in terms of time between the arrow release and arrow impact, not the physics of kinetic energy.
Today, arrow speed is largely dictated by our bows (as measured by ATA or IBO standards). Sure, smaller, lighter arrows can bump velocity up a few fps, but the gains are relatively marginal and the trade-off is usually reduced bow efficiency (heavier arrows utilize more potential bow energy than do lighter arrows) and a definite reduction in impact (kinetic) energy, which translates directly into reduced penetration potential.
That’s going the wrong way, as lightweight arrows absorb less bow energy and can lose speed faster as they travel downrange.
Heavier arrows, of course, produce the opposite effect: arrow speed slows down and bow efficiency goes up. The reduced speed (velocity) has a negative affect on impact energy, BUT that reduction in the velocity variable of the kinetic energy formula is offset by the increase in arrow weight (mass). Heavier arrows will always impact with more energy than lighter arrows regardless of the distance to the target. Is the offset enough to improve penetration? That’s where the math comes in. Without getting all scientific, know that speed isn’t the final arbiter of penetration, and that lightweight setups are the enemy of penetration—it’s a balance of weight and mass that combines for ideal penetration, all things being equal.
All things, though, aren’t equal. This is where friction comes onto the scene.
Friction reduces speed during arrow flight and influences arrow penetration into big-game animals in three ways. The first has to do with the actual diameter of the shaft. The larger the shaft diameter, the more surface area there is to slow the arrow down as it moves through the air. This is the friction along the length of the shaft as it “punches” through the atmosphere. Call this linear friction, and it means a loss of impact energy when the arrow reaches the target.
Second, the bigger the shaft diameter the more crosswind friction will move the arrow away from your intended point-of-impact. It will also steal a tiny amount of speed. Again, penetration suffers.
Finally, there is the friction coefficient of the shaft as it enters and passes through an animal. This is related to the outside dimension of the shaft (the greater the surface area the greater the friction) as well as the relative lubricity of the shaft finish (the coarser the finish the greater the friction).
As you can see, while maximum penetration is the primary objective of the ethical bowhunter, meeting that objective requires us to consider a plethora of variables. In the end, a maximum-penetration shaft won’t be the lightest or the heaviest shaft, but an equitable balance between the two (consider something in the 10 to 16 grains-per-inch range). A good-penetrating and accurate shaft should also not be overly thick to minimize crosswind and lateral friction as it travels downrange. This is especially critical if you are a Western bowhunter routinely shooting in the 40-yards-plus zone. Remember that sufficiently weighted small-diameter shafts also promote penetration by reducing friction as they pass through tough hide, bone and internal organs. Finally, a slick finish is another asset for penetration, utilizing the inherent lubricity of an animal’s body fluids to help the shaft speed along to the exit side.
So, now we are back in the archery pro shop or sporting goods store, trying to find a dozen shafts to buy. We want to locate a set in the 10 to 16 GPI range that is as thin as we can get, correctly spined for our bow’s draw weight and length, and boasts a super-slick finish. Granted, it’s not the easiest combination to find, but the closest that we’ve come to this ideal is Easton’s FMJ series shafts.
“FMJ” stands for Full Metal Jacket, and being from Easton, you can guess that the jacket is an aluminum alloy. Bonded to the inside of the aluminum tube is a carbon core.
The concept of the FMJ series arrows is to give bowhunters the strength and resilience carbon arrows offer in smaller diameters but with the low friction co-efficient and precision of aluminum arrows to deliver unrivaled penetration and accuracy. In short, the FMJ addresses all of the variables that we’ve discussed that affect penetration, and wraps them up in a single platform.
There are several FMJ models offered, from the 6mm reduced-diameter FMJ and the 5mm FMJ Camo Hunter (remember that color?) down to the micro-diameter 4mm FMJ Deep Six—perhaps the pinnacle shaft for open-range Western bowhunting, where crosswind is almost always a guarantee. And for the rising tide of traditional bowhunters, the FMJs present the optimal recipe because they offer the straightness and durability of carbon, with the added weight and reduced friction of small-diameter aluminum. Again, they make good on that optimal balance of weight and speed that’s so critical for maximum penetration on big game.
Finding the right arrow that fits your needs, hunting style and budget is no easy task when dealer shelves present you with so many options. So, rather than play pin the tail on the donkey and hope that you make the right choice, try taking a different approach this season. Remember that penetration is king in the bowhunting world. That means looking for shafts that balance weight and speed for maximum downrange kinetic energy, and are built with considerations for friction reduction to further promote penetration. Get that combination dialed in and the rest is up to you.
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