Low Poundage Bow Hunting Considerations
There are many options of compound bows available for the modern day bowhunter; from youth to seasoned hunter, short or tall, young and old. Archers who shoot bows with a draw weight of 50-pounds or more and with a draw length of 27 inches or more have unlimited options in rests, arrows, and broadhead selections. However, bow hunting has steadily risen in popularity over the last decade among hunters; especially women and youth hunters. Women and youth bow hunters are no longer considered novice hunters, this elite group of hunters has evolved into diehard hunters requiring quality gear engineered for peak performance in the field; gear that is more often in demand for lower poundage bow hunting.
As the demand for lower poundage and shorter draw length bows escalated, technology and engineering evolved to meet that need resulting in more efficiently designed bows and equipment. Bows such as the Quest Radical gives growing youth hunters room to expand with a draw length of 17.5” to 30” with draw weights varying from 15-pounds to 70 pounds. For those seasoned smaller framed hunters, bows like the Quest Storm offers a 23” to 27.5” bow and a 30-pound to 70-pound draw weight, making this bow one of the most versatile in its class. Advancements in design technology and materials have resulted in many quality bow choices for the small framed, lower poundage bow hunters.
Most states have regulations that require a minimum amount of poundage or require arrows of a minimum grains per inch (GPI) to hunt game in that state; usually around forty pounds. There are a cumulative number of factors that add up resulting in an ethical shot on wild game. Those factors start from properly fitted gear, appropriate set-up, arrow weight, broadhead type, archer’s form, shot distance and, of course, shot placement.
Low Poundage Bow Sense | Understanding Kinetic Energy and Momentum
Kinetic energy and momentum are key to the weight and speed of an arrow and its penetration potential, but they are not synonymous. With KE, speed is emphasized overweight, whereas momentum emphasizes weight over speed. These individual calculations are formulated by using the speed of the arrow and the arrow’s weight in grains. It is important to use the correct arrow and broadhead weight in grains and the accurate speed of the bow. Any archery shop can weigh an arrow and broadhead and most shops will have a chronograph to shoot an arrow through to obtain the accurate speed of an arrow.
Kinetic energy (KE), the energy of motion, is the energy of an object as a result of its speed and mass. KE is measured in foot-pounds (ft-lbs); the amount of energy needed to employ a one-pound force for a distance of one foot. The standard formula for KE is:
FPS2 x Weight of Arrow/450,240 = Arrow’s Kinetic Energy
This formula explained is the total weight of the arrow in grains, multiplied by the speed of the arrow, divided by the constant sum of 450,240, resulting in the KE of the combination. The total weight of the arrow is the arrow plus the broadhead. For instance, using a 500-grain total weight arrow at a speed of 250 feet per second (fps), the calculation for KE would be:
- Square the feet per second (fps) of the arrow first. Multiply the speed of the arrow squared by the total grain weight of the arrow:
2502 squared (62,500) multiplied by 500; resulting in the sum of 31,250,000
- Divide the resulting sum of 31,250,000 by the constant sum of 450,240 which will result in the arrow’s kinetic energy of 40 foot pounds.
31,250,000/450,240 = 69.40 ft-lbs
Momentum is the measurement of the force of a forward moving object. Momentum is measured in slug-feet per second; a unit of mass that accelerates by one foot per second upon a one-pound force. The standard formula for momentum is:
Weight of Arrow x Speed/225,400 = Arrow’s Momentum
This formula explained is the total weight of the arrow in grains, multiplied by the speed of the arrow, divided by the constant sum of 225,400, resulting in the momentum. The total weight of the arrow is the arrow plus the broadhead.
Again, using a 500-grain total weight arrow at a speed of 250 feet per second (fps), the calculation for momentum would be:
- Multiply the weight of the arrow by the speed:
500 multiplied by 250; resulting in the sum of 125,000
- Divide the resulting sum of 125,000 by the constant sum of 225,400 which will result in the arrow’s momentum of .55 slug ft./sec.
125,000/225,400 = .55 slug ft./sec.
With kinetic energy and momentum explained, archers can decide if they need to adjust, increase or decrease, the weight of the arrow for the best performance with the bow they are hunting with; however, keep in mind the minimum grains for the bow’s draw weight (see below).
Low Poundage Bow Hunting | Arrow Selection
If an archer is comfortably pulling back and shooting their maximum draw weight and an increase is unlikely, a heavier arrow will lose momentum but will increase KE offering better penetration than a lighter arrow with a higher momentum. It is important to keep in mind that shooting an underweight arrow can cause critical effects on a bow; similar to dry-firing a bow. This is the result of the arrow not providing the needed resistance to the stored energy in the limbs and strings of the bow, slowing the resistance down and transferring the energy to the arrow.
Archers who shoot lower poundage and shorter draw length bows will find that lightweight arrows result in bows transferring less energy to the arrow which results in excess energy creating unwanted noise and vibration. When choosing an arrow weight, using the International Bowhunting Organization (IBO) standards will ensure an archer is using a sufficient weight arrow. The IBO standard is five grains per pound minimum; arrow weight, including tip, must be at least five times the bow’s draw weight.
IBO Minimum Arrow Weight Standards
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*Includes tip weight.
Air resistance results in slight deceleration of lighter arrows. Heavier arrows will lose momentum but will result in more KE down range because the bow can transfer a higher percentage of stored energy to the arrow. The diameter of arrows is also an important factor in choosing an arrow for maximum penetration.
Best Broadheads for Low Poundage Bows
Opinions on broadheads run the gamut. There are two types of broadheads for compound bows; fixed blade and mechanical broadheads. Cut on contact fixed blade broadheads with a smaller cutting diameter are going to offer maximum penetration when lower poundage bow hunting; 50 pounds and lower.
In general, many professional bow technicians will refrain from suggesting mechanical broadheads for lower poundage and shorter draw length bows. Although there are several mechanical broadheads on the market that are engineered and designed for lower KE bow set ups. It is important to remember that deployment of mechanical blades will absorb some of the energy of the arrow. Another factor in energy loss is found with larger cutting diameters on a broadhead which require more energy to penetrate hide, bones, and organs. Fixed blade broadheads with a cut on contact tip and a smaller cutting diameter of 1 ½” or less, like that of the G5 Montec and G5 Montec CS, result in higher performance than that of equal diameter mechanical blades. The G5 Striker with a cut on contact tip and fixed interchangeable blades offers superior performance with lighter poundage bows.
The accuracy of arrow and broadhead placement is critical to a successful hunt, however, having the proper arrow and broadhead to perform the perfect shot is key.
Arrow Rests
Arrow rests that offer the least amount of contact with the arrow will assure no loss of energy of the arrow. Drop-away arrow rests will allow perfect drag-free shooting. Not only do drop-away rests eliminate energy loss, drop away rests also offer full containment of the arrow, keeping the arrow in position on the rest no matter the position of the bow in the stand or on-foot scouting on the heels of the game animal being pursued.
Ultimately, nothing will factor higher in shot placement and ethical kills than that of practice, perfect practice; and more practice. Smaller framed archers and those bow hunters who bow hunt with lower poundage and shorter draw length bows will always have a handicap against them compared to those bow hunters with longer draws shooting higher poundage. Fortunately, in the last decade bow and archery gear companies such as G5 Outdoors have engineered and designed equipment for this class of hunters. Gone are the days where this class of bow hunters are limited to youth bows or bows that offered very little adjustment capabilities. Low poundage bow hunting gear and technology is a must for the expanding niche in hunting.