A few weeks ago I was reading one of my favorite archery magazines when I noticed an ad by an arrow manufacturer. The ad boasted of some very impressive arrow velocities, speeds well above 320 feet per second. This piqued my curiosity! Upon further investigation I read that they were shooting arrows which were very light. As a matter of fact, too light for my bow. I wondered how this could be, so the manufacturer and spoke with a representative.
His explanation was that the bows this manufacturer builds are warranted down to a dry fire! Until now, something unheard of in the industry. The challenge was had been to find an arrow with a spine (arrow shaft flex) stiff enough to handle radical cams at high draw weights in a light weight arrow. They couldn’t find one, so they made one. These arrows when combined with one of their bows produce an extremely fast shooting system.
As I looked at the ad in depth, I found that it could be misleading and potentially, down right dangerous for someone not possessing a thorough knowledge of the limits of their particular equipment. While there may be some controversy over whether it is safe to shoot an arrow which is too light, based on the manufacturers limits, it’s not my objective to bring an end to that controversy but to educate. According to many bow manufacturers, an arrow weight of less than 5 grains per pound of draw weight is extremely dangerous. Most bows are not designed to handle arrows that light.
Would you shoot your rifle with a gunpowder load, which EXCEEDS the manufacturer’s limits? Or, would you shoot your bow with an arrow, which is BELOW the manufacturers limits?
When the bowstring is released, the energy must go somewhere other than into the bow it self. Most bow manufacturers design their bows for a specific minimum arrow weight. In most cases the total arrow weight (shaft, insert, vanes, nock, etc…) needs to weigh at least 5 grains of arrow weight for every pound of draw weight. For instance, if a bow’s draw weight is 70 pounds, the arrow weight must be a minimum of 350 grains. (70 pounds X 5 grains = 350 grains).
While there is some controversy around whether it is “safe”, or even wise, to shoot below the bow manufacturers limits there is something greater that can be learned. Know your equipment and the basic rules for setting it up!! For example: I set my bow up for two different purposes in mind; one for indoor spot shooting, and the other for big game hunting. The two setups are very different. For spot shooting I’m not concerned with arrow speed, so I shoot heavier larger diameter arrows. My only concern is spot shooting is accuracy. For hunting, speed and accuracy are my goals while keeping the minimum arrow weight in mind for the draw weight that I have set.
My spot league setup is: draw weight 60 lbs with an arrow weight 400 grains. Using our formula for figuring the minimum arrow weight from earlier, my minimum arrow weight should be 300 grains (60*5=300 grains). With this setup I’m well within the 5 grain per pound limits for my Hoyt UltraTec.
For my hunting setup I’ll set my draw weight to 68 lbs. This setup requires a minimum arrow weight of 340 grains. So how do I find the arrow I need? Reverse engineer the weight. For example, let’s say I plan on using Easton Axis 400 arrows. I know the arrow weight by multiplying the shaft length, 26 inches in my case by 8.95 grains per inch for a shaft weight of 232.7 grains. The rest of the arrow components are: insert – 16 grains, nock – 9 grains, vanes – 18.3 grains. I plan on using Rocket Ultimate Steel broad heads weighing 75 grains.
351 grains falls nicely within the design specifications of my Mathews Switchback, with room to spare. With this setup I can go as high as 70 pounds of draw weight and still be within the manufacturer’s design limits of my bow.
So, the moral of this story is: Know your equipment and research what you read. When in doubt, talk to your local pro shop and educate yourself.
I’ll see you on the mountain.