Broadhead tuning guide
Diagnose why your broadheads are not grouping with field points and get the exact fix in priority order — covering fixed blades, walk-back tuning, FOC, and broadhead runout.
Companion to Paper Tuning a Bow — complete that guide first if your bow has not yet been paper tuned. Broadhead tuning is the final confirmation step, not the starting point.
Why broadheads hit differently than field points
Field points are aerodynamically neutral — their small pointed profile creates almost no steering force even if the arrow is wobbling slightly. Fixed-blade broadheads are the opposite. Their exposed cutting diameter acts like a small wing, steering the arrow in the direction of any residual flight error from the first yard of the shot.
This means a bow that groups field points well at 40 yards can still scatter fixed blades — not because anything is wrong with the broadheads, but because the bow is slightly out of tune and the field points were forgiving enough to hide it. Broadheads expose the truth.
Confirm these before starting broadhead tuning
None of the fixes below will hold if these are not already true. Check all four first.
Broadhead impact diagnosis tool
Shoot 3 field-point arrows at a dot from 20 yards, then shoot 3 broadhead arrows at the same dot. Describe the broadhead group's position relative to the field point group below.
Results update automatically as you make selections.
Tuning session log
Record each adjustment and result so you can track what's working — and reverse anything that made things worse.
No adjustments logged yet. Add your first entry above.
Group offset tracker
Log your broadhead vs field point offset at multiple distances. The pattern tells you what kind of problem you have — not just that you have one.
No readings logged yet. Add a distance reading above.
Walk-back tuning — the fastest centershot fix
Walk-back tuning is the most reliable method for setting final centershot. It reveals horizontal drift that builds up over distance — the exact problem that causes broadheads to diverge from field points at hunting ranges.
Setup
Run a strip of vertical tape down the centre of a large target. Stand at 10 yards, use your top pin only, and aim at a dot at the top of the tape. Shoot one arrow, then step back to 20, 30, and 40 yards — always aiming at the same dot with the same top pin.
Reading the result
If your arrows walk left as you move back, your centershot is too far right — move the rest left. If they walk right, move the rest right. Arrows should walk straight down the tape as distance increases. A perfectly set centershot produces a vertical column.
Why it matters for broadheads
A centershot that is off by 1/32" may not show up at 20 yards with field points, but at 40–50 yards with fixed blades steering the arrow, that same error produces a 4–6 inch impact divergence. Walk-back tuning catches this error directly.
After walk-back tuning
Once your walk-back arrows run straight, re-verify your paper tune — moving the rest for centershot slightly changes the paper tear. Then re-test broadheads at 40 yards. Most broadhead divergence problems are solved at this point.
Distance amplification calculator
A small offset at 20 yards grows predictably at longer distances. Enter your known offset to see whether it falls within a hunting-ethical margin at your maximum shooting distance.
Results update automatically.
Fixed blade vs mechanical — tuning differences
The type of broadhead you shoot changes how much tuning effort is required and which problems you're most likely to encounter.
| Factor | Fixed blade | Mechanical |
|---|---|---|
| Sensitivity to bow tune | High — exposes every flight error | Low — flies similarly to field points |
| Sensitivity to FOC | High — needs 10–15% for stable flight | Low — tolerates 8–12% FOC |
| Spin-test importance | Critical — one bad head ruins the group | Important but less critical |
| Walk-back tuning benefit | Very high — often the decisive fix | Moderate — useful but rarely essential |
| Divergence from field points | Common even from well-tuned bows | Uncommon — usually indicates a real problem |
| Impact of blade diameter | Larger blades = more steering force | Negligible until blades open |
If you shoot mechanicals and they are not grouping with field points, the cause is almost always a genuine tune problem. Return to paper tuning and confirm a bullet hole before diagnosing further.
FOC and its effect on broadhead flight
FOC (front of center) is the percentage of your arrow's weight that sits forward of the balance point. For fixed-blade broadhead hunting, this number matters more than most archers realise — not for penetration but for flight stability at hunting distances.
| FOC range | Flight characteristic | Broadhead suitability |
|---|---|---|
| Under 8% | Tail-heavy, susceptible to steering | Poor for fixed blades beyond 25 yards |
| 8–10% | Marginal — fine for mechanicals | Borderline for fixed blades |
| 10–15% | Stable, self-correcting flight | Ideal for fixed blades at hunting distances |
| 15–20% | Nose-heavy, reduced vane correction | Good for penetration, acceptable for fixed blades |
| Over 20% | High FOC — vanes less effective | Specialist setups — verify at full distance before hunting |
The fastest way to raise FOC without changing arrow shafts is to increase insert weight. Use the FOC Calculator to find where your setup sits, then experiment with heavier inserts if you are below 10%.
🛒 Brass and steel arrow inserts on Amazon — a 50–100 grain brass insert can shift FOC by 2–4 percentage points on a typical hunting arrow.
Fixed blade tunability selector
Before buying broadheads, know how hard they will be to tune. Select your cutting diameter and ferrule type to see the tunability rating and what to expect.
Results update automatically.
How to spin test broadheads correctly
The fingernail test
Place the broadhead tip on your fingernail at a slight angle and flick the nock end to spin the arrow. Watch the ferrule and blades — any wobble means the head is not running true. Do this for every individual broadhead before you shoot it.
What causes wobble
Bent blades, a ferrule that is not perfectly concentric, a crooked insert, or a bent arrow shaft. For fixed blades with replaceable blade sets, try swapping the blade set first — it is often the blade collar that is slightly off, not the ferrule itself.
One-piece broadheads
One-piece fixed blades have no moving parts to go wrong, but the tip-to-ferrule alignment can still be off from manufacturing. If a one-piece head wobbles on the spin test, discard it — there is no adjustment to make.
After the spin test
Shoot each labelled broadhead-tipped arrow through paper at 6–8 feet. Each should produce a near-bullet hole if your bow is tuned. An arrow that tears badly with a broadhead but clean with a field point has a bad insert alignment or a bent shaft — not a bow problem.
What you need for broadhead tuning
Most of this can be done with gear you already own. The items that come up most often:
Fixed blade
broadheads — if you are consistently fighting divergence, a lower-profile fixed blade (1 1/8"
cut) is dramatically easier to tune than a 1 3/4" head.
Field points
(matched weight) — always use field points that exactly match your broadhead weight for accurate
comparison testing.
Heavy brass or steel
inserts — the fastest way to raise FOC if your fixed blades are scattering at longer
distances.
Micro-adjustable arrow
rest — walk-back tuning corrections require precise incremental movement; fixed-position rests
make this very difficult.
Grain scale —
weigh field points and broadheads to confirm they are truly matched in weight before testing.
Broadhead tuning — frequently asked questions
Why do my broadheads hit in a different place than my field points?
Fixed-blade broadheads act as forward steering surfaces — their blade surface area amplifies any arrow flight error that field points' small profile conceals. The most common causes are: the arrow not leaving the bow perfectly straight, centershot slightly off, a broadhead that is not running true, or FOC too low. Use the diagnosis tool above to identify your specific situation.
Why do fixed blades diverge more than mechanicals?
Mechanicals keep their blades folded in flight and behave aerodynamically like field points until impact. Fixed blades expose their full cutting diameter from the moment they leave the bow — any lateral movement is immediately amplified. A bow that shoots mechanicals well may still need further tuning for fixed blades.
What is walk-back tuning and why does it help?
Walk-back tuning verifies your centershot by shooting at a single vertical target line from increasing distances with your top pin. Horizontal drift as you step back reveals a centershot error that field points at 20 yards hide but fixed blades at 40–50 yards expose. Correcting centershot via walk-back is often the single most effective broadhead divergence fix.
How does FOC affect broadhead flight?
FOC below 10% makes an arrow tail-heavy and susceptible to blade steering beyond 30 yards. The fix is usually heavier inserts — 50–100 grain brass or steel inserts can shift FOC by 2–4 percentage points without affecting spine selection. Use the FOC Calculator before experimenting with component weights.
Do I need to spin test every broadhead?
Yes, for fixed blades. Any wobble on the spin test means the head is not running concentric with the shaft — it will steer regardless of how well your bow is tuned. One off-true broadhead in a group makes it impossible to diagnose whether your bow or your broadheads are the problem.
Should I move my sight or my rest when broadheads diverge?
Always move the rest, not the sight — until the bow is genuinely tuned. Moving the sight to compensate hides the underlying problem and creates an arrow that planes unpredictably at different distances. Fix the root cause so that field points and broadheads hit together, then adjust the sight for final zero.
My broadheads group well but hit 3 inches left at 40 yards. What do I adjust?
Tight broadhead groups consistently offset from field points indicate a centershot problem. Run a walk-back tune — shoot at a vertical tape line from 10, 20, 30, and 40 yards with the same top pin. If arrows drift left as you step back, move your rest left in 1/32" increments until they walk straight. Then re-test broadheads at 40 yards.
My mechanicals group with field points but my fixed blades don't. Normal?
Yes, very common. Mechanicals behave aerodynamically like field points. Fixed blades steer in the direction of any flight imperfection. Walk-back tune for centershot, check FOC, spin-test the fixed blades, and paper tune once more specifically with the fixed blade attached.