Updated September 15, 2025 · ~7 min read
Choosing the right arrow with a broadhead is not a minor detail: it's the key to an accurate, ethical, and penetrating shot. The right combination of spine, length, weight, fletching, FOC, and let-off transforms the bow and arrow into a cohesive system. This guide explains the criteria, setups for compound and traditional bows, and current trends in the United States.
The importance of choosing an arrow
In bowhunting, the arrow is more than just a projectile. With a hunting broadhead , it becomes the element that makes the difference between a tight group and a wild shot. An improperly fitted combination of spine (stiffness), length, weight, fletching, or FOC (Front of Center) will result in poor trajectory, noise, and penetration.
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Spine and stiffness
Spine refers to the arrow's stiffness. If it's too flexible, it bends at launch and veers off course; if it's too stiff, it stalls. The ideal spine depends on three main factors:
- Bow power : the higher the power, the stiffer the arrow needs to be.
- Arrow length : the longer it is, the more the arrow "flexes" (lever effect) → this is compensated for by a stiffer spine.
- Tip weight : 125–150 gr makes the arrow more flexible; 100 gr makes it more rigid.
Practical examples (arrow 29.5") :
- 50–60 lbs + 100 gr : aim for a spine 340 .
- 50–60 lbs + 125 gr : between 300–340 (prefer 300 for more stability).
- 60–70 lbs + 100 gr : aim for a spine 300 .
- 60–70 lbs + 125 gr : between 250–300 (at high let-off, 250 is often safer).
Quick reminder : powerful bow + long arrow + heavy point ⇒ stiffer spine. Less powerful bow + short arrow + light point ⇒ as flexible a spine as possible.
FOC (Front of Center)
The FOC ( Front of Center) is the percentage of weight at the front of the arrow. Aiming for 10–15% in hunting often offers the best compromise between stability and penetration. The American trend is towards high-FOC ( 15–20%+ ) using heavier inserts and points, which is useful for big game. Note: the higher the FOC, the more important it is to match the spine size and fine-tune the arrow.
Plumage and stabilization
The vanes/feathers stabilize the arrow and correct small errors in exit.
Compound bow
- Mechanical points : 2–2.5" vanes are sufficient.
- Fixed points : 3–4" vanes, ideally helical to counteract the lift of the blades.
Traditional bow (recurve/longbow)
- Natural feathers : 4–5" (up to 5.5" depending on power), very tolerant of contact with the window/carpet.
Rule : the wider and more fixed the hunting blade, the more feathering surface area is needed.
Let-off and impact on the spine
The let-off (reduction of tension at the anchor) influences the tolerance of the bow-arrow system.
- High let-off (80–90%) : very comfortable, but less tolerant of spine and mounting deviations → requires rigorous selection.
- Lower let-off (65–75%) : more “aggressive” at the start from the rope, often more permissive on small imperfections.
Choosing an arrow at 90% vs. 70%
- At 90% : if you are "between two" chart boxes, increase the stiffness ; favour a heavier setup (~8–9 gr/lb +), straightness ≤ .003", and test with your hunting points.
- At 70% : more versatile configuration; the "chart" spine is often suitable; it is possible to lighten (~6–7 gr/lb) if speed is paramount; tuning is generally simpler.
Corrections and adjustments depending on the type of bow
Compound bow
- Tuning : center-shot/arrow rest, alignment, cam synchronization.
- Suitable plumage : 2–2.5" (mechanical) / 3–4" helicopter (fixed).
- High let-off : don't hesitate to stiffen the spine by one notch.
- Real test : compares training points vs hunting points on a target.
- USA trend : micro-diameter shafts (4–5 mm OD) → less wind drift, better penetration.
Traditional bow (recurve/longbow)
- Spine often more flexible (archer's paradox).
- Heavier arrows: approximately 10–12 gr/lb for stability and penetration.
- Natural feathers 4–5" in helical; aluminium appreciated for its regularity, carbon also widely used.
Quick and practical tips
- Constant weight between arrows: tolerance of 1–2 gr max.
- Alignment of the points : screw/center perfectly; a point that "swims" = guaranteed gap.
- Compare on target : always validate training vs hunting before the season.
- FOC : aim for 10–15% ; High-FOC ( 15–20%+ ) if spine/tuning follow.
FAQ — Frequently Asked Questions
I'm torn between two spines on the chart: which one should I choose?
With fixed points , high let-off , and/or a large FOC , choose the stiffer one . With mechanical points and ~70% let-off, the more flexible of the two may be suitable.
Are short vanes sufficient to stabilize a fixed point?
Generally not. Fixed tips act like ailerons; prefer 3–4" vanes in helicopters , especially at longer distances and in windy conditions.
What focal length (FOC) should I aim for when using a general-purpose roe deer mount?
12–15% works very well. Above that (15–20%+), it performs well but requires a stiffer spine and impeccable tuning.
Conclusion
With broadheads, every detail counts. Calibrate your spine based on power/length/point, choose a suitable fletching , manage your FOC , and consider the effect of let-off (90% demanding, 70% more forgiving). North American trends—high-FOC, micro-diameter arrows, optimized vanes—aim for consistency, ethical shooting, and penetration. Always validate on the target with your true broadheads.