Arrow Spine: The Spec That Determines Accuracy
Arrow spine measures shaft stiffness — specifically how much (in thousandths of an inch) the shaft deflects when a 1.94 lb weight is hung from its center while the shaft rests on two points 28 inches apart. This is the industry-standard AMO/ATA spine test method.
Counterintuitively, lower spine numbers mean stiffer arrows: a 300 spine arrow deflects 0.300 inches (stiffer), while a 500 spine arrow deflects 0.500 inches (more flexible). Common spine ratings: 250, 300, 340, 400, 500, 600.
Why spine matters: When a compound bow fires, the arrow bends (the "archer's paradox") as it clears the riser. An arrow with incorrect spine will bend either too much or too little, causing inconsistent contact with the rest, erratic flight, and poor groups. Correct spine selection is the foundation of arrow accuracy.
Reading Arrow Spine Charts
Manufacturers publish spine selection charts mapping draw weight and draw length to recommended spine. Here's a simplified guide for compound bow hunters:
| Draw Weight | Draw Length | Recommended Spine |
|---|---|---|
| 40–50 lbs | 26"–28" | 500 spine |
| 50–60 lbs | 27"–29" | 400 spine |
| 60–70 lbs | 28"–30" | 340 spine |
| 70–80 lbs | 29"–31" | 300 spine |
| 80+ lbs | 30"+ | 250 spine |
Factors that affect ideal spine selection: Point weight (heavier broadheads require stiffer spine), arrow length (longer arrows need stiffer spine), and shooting style (fingers vs release aid). Always use the manufacturer's specific chart for the arrows you're buying — these charts vary somewhat between brands.
Arrow Weight in Grains: Penetration vs. Speed
Total finished arrow weight (shaft + insert + nock + vanes + point) is measured in grains (1 grain = 0.0648 grams). This directly determines kinetic energy, momentum, and flight trajectory.
| Arrow Weight | Speed | Penetration | Noise | Best For |
|---|---|---|---|---|
| Under 350 gr | Fastest | Lowest | Loudest | 3D target, maximum speed |
| 350–450 gr | Fast | Good | Moderate | Target hunting combo |
| 450–550 gr | Moderate | Excellent | Quiet | Deer, turkey hunting (recommended) |
| 550+ gr | Slower | Maximum | Very quiet | Large game, traditional archery |
Bowhunting rule of thumb: Aim for 6–8 grains per pound of draw weight total arrow weight. At 60 lbs draw: 360–480 grain arrow. Most experienced bowhunters prefer the 450–500 grain range for whitetail deer — it provides excellent penetration, good kinetic energy, and noticeably quieter shots.
Carbon vs Aluminum vs Hybrid Shafts
Carbon (The Modern Standard)
Carbon fiber arrow shafts have dominated hunting archery since the late 1990s. Advantages: light (fast), stiff-to-weight ratio is excellent, don't bend (carbon shafts either survive or break cleanly — no bent arrows that appear straight), consistent diameter throughout length, and available in micro-diameter options that reduce wind drift and penetrate hide better.
Disadvantage: Cannot be straightened if bent. Inspect for cracks before every use — a cracked carbon shaft can splinter and cause serious injury.
Aluminum
Traditional standard before carbon. Advantages: can be straightened if bent (aluminum bows slightly), extremely consistent tolerances (some target archers prefer aluminum for this reason), slightly more forgiving for recurve/traditional finger shooters. Disadvantages: heavier than carbon, bend rather than break cleanly, lose some straightness over time.
Carbon/Aluminum Hybrid (Easton ACC, ACE)
Aluminum core wrapped in carbon. Combines aluminum's consistent straightness tolerance (+/- 0.001" on premium ACC series) with carbon's stiffness. Preferred by Olympic recurve and compound target archers who need maximum consistency. Premium pricing. Most hunters don't need these but competitive 3D archers often shoot ACC or ACE.
Fletching and Vanes
- Plastic vanes: Standard for compound hunting. Quiet, waterproof, consistent. 2-inch to 4-inch vanes with helical or offset orientation for rotation that stabilizes broadheads.
- Natural feathers: Preferred for traditional archers and recurve shooters — softer contact with arrow rest, self-clearing on longbows. Feathers are affected by rain (they collapse when wet) so not ideal for hunting in wet conditions.
- Helical vs straight: Helical fletching induces spin-stabilization. Essential for fixed-blade broadheads. Straight fletching flies faster but provides less stability. Use helical for hunting, straight for field points only.
Top Arrow Picks
Common Arrow Selection Mistakes
Frequently Asked Questions
What does arrow spine mean and how do I choose the right spine?
Arrow spine measures shaft stiffness — specifically how much the shaft deflects in thousandths of an inch under a standard load. Lower numbers mean stiffer arrows (300 is stiffer than 500). You select spine based on your bow's draw weight, draw length, and arrow length using the manufacturer's spine chart.
How heavy should my hunting arrows be in grains?
Most hunting recommendations target 400–500 grains total finished arrow weight. Heavier arrows carry more kinetic energy, penetrate better, and shoot quieter. Aim for 6–8 grains per pound of draw weight: at 60 lbs, target 360–480 grain total arrow weight.
Should I use carbon or aluminum arrows for deer hunting?
Carbon arrows are the standard for modern hunting — lighter, stiffer, and more consistent than aluminum at equivalent price points. Aluminum is still valued by traditional archers who prefer the ability to straighten bent shafts. Carbon/aluminum hybrids are used by competitive target archers who need maximum consistency.
Sources & Further Reading
- Easton Technical Publications. "Arrow Spine Selection Guide." eastonarchery.com
- Archery Trade Association. "Arrow Spine Standard AMO S2-1991." archerytrade.org
- Lancaster Archery Supply. "How to Choose Arrow Spine." lancasterarchery.com
- Bowhunting.com. "Arrow Selection Guide for Deer Hunters." bowhunting.com
- 3Rivers Archery. "Traditional Arrow Selection for Recurve and Longbow." 3riversarchery.com
