WebXtra September: Bow Reports – Updating Our Specs

Bow ReportsTo bring Inside Archery’s Bow Reports data up to date and abreast of arrow technology, senior editor Patrick Meitin is making several changes to our original test format.

Bow Specifications and Test Criteria

First, Meitin replaced the 29-inch draw length with a 30-inch draw length, but left the 70-pound draw-weight intact. This better reflects the industry’s ATA standards, and more accurately compares arrows to each manufacturer’s advertised ATA speeds. All arrows used in Meitin’s tests wear weight-matched, 100-grain field points.

Meitin obtains average arrow speeds with a Spot-Hogg Hooter Shooter and Pro Chrono Plus digital chronometer set 5 feet in front of the bow. He weighs the arrows on a balance scale that’s accurate to .10 grains. The Hooter Shooter guarantees a consistent draw length and release, eliminating human error. He shoots the same arrow a minimum of five times to obtain an average, and adds more shots if the low/high mean is inconsistent.

Note: Meitin equips all test bows with a G5 Meta peep sight and string loop to consistently evaluate shooting comfort, forgiveness and accuracy. Obviously, adding weight to the middle of the bowstring slows arrows speeds. In contrast, ATA ratings are established without these standard bowstring add-ons, which inflate speeds beyond those of hunt-ready bows.

Test Arrows and Assembly

Meitin also changed the test-arrow lineup to better reflect current arrow styles and to represent a wider array of popular brands. He makes every effort to include the major arrow manufacturers, while also creating even weight spread and minimal overlap. This more accurately represents bow performance when shooting the heavier arrows popular with many bowhunters today, as well as the speed arrows many 3-D target archers and long-range bowhunters prefer. Meitin cuts all arrows to 29 inches because current drop-away rests create an overdraw effect that’s ideal for 29-inch arrows. He assembles all arrows with components supplied by the manufacturer.

By arranging arrows from the heaviest finished weight to lightest, the discrepancies between grain-per-inch (gpi) numbers and finished weight can get confusing. For instance, Alaska Bowhunting Supply’s GrizzlyStik Momentum U-FOC 330 has a 10.5 gpi (empirical average based on overall length of the tapered carbon shaft), while the 11.3 gpi Easton FMJ 340 weighs less overall. Arrow accessories create these differences. The Momentum, for example, uses a 78-grain brass insert to boost F.O.C., while the FMJ uses a 16-grain aluminum H.I.T. insert.

Besides inserts (long or short, internal or bulkier outsert, aluminum, steel or brass material), an arrow’s weight is affected by fletching and nock systems (larger or smaller, absence or addition of nock sleeves or bushings). Meitin fletches his test arrows with popular 2-inch, high-profile vanes with no decorating wraps beneath. One small deviation: The Beman ICS Hunter Pro holds a one-piece Blood Vane three-fletch sleeve, which slightly increases its weight.

Meitin’s lightest arrows, weighing 332 and 301 grains, are lighter than the 5-grains-per-inch of draw weight minimum that’s generally recommended by bow manufacturers, and are used for illustration purposes only.

Why Kinetic Energy?

Finally, in Meitin’s opinion, kinetic energy poorly indicates penetration potential or big-game performance, because raw speed unduly influences it. However, the industry has universally adopted kinetic energy as an indicator, and it provides relative apples-to-apples comparisons. If we substituted the Momentum formula for KE (a better indicator of big-game performance potential), the seemingly inconsistent spikes in energy occasionally seen in lighter shafts would likely vanish, and show a more even energy curve from heaviest finished-arrow weights to lightest.

Visit Us On FacebookVisit Us On InstagramVisit Us On TwitterVisit Us On Youtube