If we want to be honest with ourselves, almost any hunting arrow has the potential to get the job done if its flight performance is predictable—meaning that we know for certain it can hit an intended point of impact if we don’t screw up the shot. After all, aboriginal people fed themselves for millennia using hand-fashioned wood and cane shafts straightened with rocks and campfires.
Of course, technological advancements in archery equipment has demanded equal advancement in arrow designs. Our hyper-sensitive, high-speed gear means that if anything is a millimeter or two out of whack, the downrange results become exponentially dismal as shooting distance increases. That’s just the mechanical stuff you can control. After that, other factors weigh in that you have no control over in a bowhunting scenario, such as wind, deflection potential when encountering grass, leaves, or other objects in the flight path, and of course, the target’s hide, muscle tissue and bone.
Needless to say, the stacking of these many variables is why things can go wrong in the field. Our task then is to minimize the variables that can degrade accuracy and terminal performance. To that end, Easton has developed an arrow that does just that.
Early this year, Easton rolled out a new bowhunting shaft that caused most of us in the archery realm to simply say, “Wow.” It is called the T64, and it’s the newest member of the company’s vaunted FMJ (Full Metal Jacket) arrow line. The name breaks down the arrow’s particulars quite nicely: Tapered, 6mm/4mm.
The T64 FMJ leads the natural evolution of the FMJ concept and the theories behind small-diameter shafts and prominent Front of Center (FOC) weight distribution. Here is arguably the most technically advanced hunting arrow ever constructed that, in one slender shaft, addresses all of the desired attributes that promote accuracy and penetration.
Being an FMJ, the T64 model is comprised of a carbon core wrapped in an aluminum jacket. Where the T64 differs from other shafts in the FMJ lineup is its profile. The arrow starts at the front end with a 6mm diameter. It remains at this diameter for about the first 6 inches before tapering to a micro 4mm diameter at the nock end. Easton was able to achieve coaxial alignment of the shaft across these two angles to +/- three milliradians is just as impressive. In short, the T64 sets a new benchmark in bowhunting shaft technology as far as material construction and tolerance control is concerned.
“OK,” you say. “Kudos to the Easton engineers, but what does this do for me?”
To answer that, let’s consider the key criteria of a top-performance bowhunting arrow.
Accuracy
Whether we’re talking ammunition or arrows, accuracy first requires manufacturing consistency. For arrows, that means absolute straightness and shaft walls that exhibit uniform material thickness, in addition to concentricity to the axis across the length of the shaft. Deviations in any of these dimensions or tolerances can upset the arrow in flight and lead to reduced accuracy—especially in today’s fast-shooting and adjustment-sensitive bows. The T64’s tight tolerances mean that it starts with the manufacturing consistency that is so essential for accuracy, making it what may be the most precisely constructed bowhunting shaft ever made.
That level of manufacturing precision establishes a solid foundation with which to introduce other features that further the T64’s accuracy potential.
Flight Stabilization (F.O.C.)
By now, most bowhunters are familiar with the importance of an arrow’s front-of-center weight distribution. This means that having more of the shaft weight skewed toward the front of the arrow significantly improves an arrow’s in-flight stability — think of a lawn dart and how that weighted front end assists in a good throw. Generally, the more weight toward the front of the shaft the more stable the arrow and the more resistant it is to forces like wind and deflection from an object, that could move it off of its flight path. There is a balance there, however, that must be maintained. The more weight up front, the quicker an arrow drops its trajectory and nose dives. For most bowhunters, a 10- to 15-percent F.O.C. is usually just right.
Often, bowhunters must install weighted inserts and/or bump up to 125-grain broadheads to achieve the ideal F.O.C. The new T64 shaft has the advantage of having an integrated F.O.C. by virtue of its tapered design that begins up front with a 6mm diameter.
Before building the raw T64 shafts, Easton tested to determine the arrow’s inherent F.O.C. With just the bare shaft (no nock, insert or fletching installed), the arrows revealed a 4.375-percent F.O.C. That’s nearly one-half to one-third of the way toward our target F.O.C. percentage. Then they tested again after the arrows were built. With a 100-grain point installed and using the standard RPS insert, the assembled arrow’s F.O.C. came in at 12.81 percent—smack in the middle of the optimal F.O.C. range for a bowhunting arrow.
Aerodynamics
Understandably, an ideal F.O.C. percentage is only part of the accuracy equation. In the field and when shooting at long distances, shaft aerodynamics play a huge part in delivering on an arrow’s accuracy potential.
We don’t have a wind tunnel to test airflow characteristics over shafts, but a solid, logical assumption is that the T64’s tapered design should prove slightly more aerodynamic than that of a straight-shaft profile. What we do know for certain from field testing is that less surface area of an arrow directly translates to its ability to resist crosswind deflection, and to a lesser degree reduce speed-robbing atmospheric friction. That means less point-of-impact shifting due to wind drift and greater retention of kinetic energy. For bowhunters who typically encounter longer shots, those are huge benefits. The T64, with its 6mm to 4mm micro-diameter final taper, finds that sweet balance of energy retention, streamlined aerodynamics, and a reduced cross section to better stay on target and deliver maximum penetration.
Penetration
An arrow’s ability to provide optimal penetration is directly related to its kinetic energy, which in turn, is determined by arrow mass and velocity. With its carbon core/aluminum sleeve composite composition like all FMJ arrows, the T64 packs a big punch in a small package. Weighing a bare T64 shaft revealed a total weight of 354.3 grains. Dividing that by the shaft’s 30-inch length puts it at around 11.8 grains per inch on our test shaft. The average gpi is 13.3 or 12.2, depending on the T64’s DF designation. That’s the kind of weight we want for a big-game arrow, and that extra heft goes a long way toward quieter shots.
Beyond the math, the T64’s tapered profile further contributes to penetration. Since the shaft starts at 6mm diameter directly behind the broadhead, the decreasing diameter of the shaft as it moves through hide and muscle tissue means significantly less friction on the shaft the farther it penetrates. A consistent-diameter shaft, by contrast, has an almost equal amount of friction applied to it throughout its passage through an animal. This means that the T64 gets a “penetration boost” by virtue of its tapered profile. And anything that adds to deeper penetration or more reliable pass-through shots is a big win in our book.
Sizes & Tuning
The T64 FMJ is offered in two deflections (spines) that covers draw lengths from 26 to 32 inches and comparative arrow spines from 400 to 300. The heavier 7.9 DF (310 spine) is available in 32 inches while the 9.5 DF (375 spine) is offered in 30 inches.
Fine-tuning can be achieved by trimming the shaft length from either end, depending on your needs. Cutting from the front, which you can safely do up to the maximum cut line indicated on the shaft, will weaken the spine. Trimming from the nock end has the effect of stiffening the spine. So, if you prefer to trim your arrows as a matter of course rather than shoot full length and maintain that heavier weight for hunting, keep that in mind before you cut.
Given the T64’s broad deflection range, we wanted to put it to the test by sending our half-dozen downrange from a 52-pound compound and a 55-pound recurve bow. We left our 30-inch, 9.5 DF arrows full length and fletched three with 2-inch plastic vanes, and three with 4-inch feathers—all with a slight offset.
The compound was tuned and sighted in for 29-inch, 400 spine 5mm FMJs weighing in at 506.9 grains, which included 75-grain Brass X HIT inserts and 100-grain points. The 9.5 DF T64s weighed 498.2 grains with 100-grain points and no additional weight. Across our shooting range, the T64s zipped like darts and shot as true as the arrows for which the bow was set up to shoot.
Moving to the recurve, our 55-pound draw weight and 28-inch draw length put us right in the zone for the 9.5 DF T64. Again, the T64s flew true and hit hard, with no discernible fishtailing from archer’s paradox recovery. It stands to reason that the F.O.C., combining with the tapered back end, allowed the fletching to more quickly stabilize the shaft than conventional straight-wall shafts. For a traditional shooter, that means less energy wasted on flight correction and more available kinetic energy for penetration.
In summary, the new Easton T64 FMJs deliver the kind of performance that we all chase in the process of refining our gear. Whether you are a compound shooter looking for that long-distance accuracy edge in the pursuit of open-range game, or are a traditional shooter that scratches for every penetration advantage that you can get — the T64 FMJ is one of the best options available today for both instances.
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