The four specs that matter, in order
1. Spine — not optional, not a preference
Spine is the calibrated stiffness of the shaft. Easton measures it by suspending an arrow on supports 28 inches apart, hanging an 880-gram load at the centre, and reading the deflection in inches — a shaft that bends 0.400″ is a “400”. Lower number, stiffer arrow.
An arrow flexes as it leaves the bow. Too weak for your setup and it over-flexes and porpoises; too stiff and it does not recover correctly. Either way your broadheads will not fly with your field points, which is the classic symptom hunters misdiagnose as a tuning problem or a bad broadhead. Easton notes that dynamic spine is affected by point and insert mass, fletching weight and bow acceleration — which is why adding a heavier broadhead can push a previously-correct arrow out of spec.
Rough orientation only, and no substitute for a selector chart: most whitetail hunters shooting 55–65 lb at a 28–29″ draw with a 100-grain point land on a 340 or 400 spine. Confirm it — do not assume it.
2. Straightness tolerance
Published as a ± figure: ±.006″, ±.003″, ±.001″. It is the manufacturing tolerance on how straight the shaft is, and it decides consistency — whether six arrows out of the same box hit the same spot.
Be honest about where it matters. Inside 30 yards with field points you will struggle to see a difference between ±.006 and ±.001. Put a fixed-blade broadhead on the front and stretch to 40 or 50 yards and it shows, because a broadhead acts like a wing and amplifies whatever wobble was already in the shaft. Buy the tighter tolerance if you shoot fixed blades at distance; save the money if you are a 20-yard timber hunter.
3. Total arrow weight
Heavier arrows carry momentum and penetrate better; lighter arrows fly flatter and forgive ranging errors. For whitetail, penetration is rarely the constraint — a properly spined arrow of ordinary weight from a 60 lb bow passes through a deer routinely.
One number to know: the Pope & Young Club’s equipment standards set a 300-grain minimum total arrow weight for record eligibility, and it is a sensible floor for hunting arrows generally. Kinetic energy is a product of arrow weight and speed, and it is the arrow’s energy at the animal that determines penetration — not the bow’s advertised IBO number.
4. Diameter and FOC
A micro-diameter shaft presents less surface for hide, muscle and rib to grip on the way through, so it penetrates better for the same weight. It also needs its own matched components — you cannot use standard inserts — which is a real ownership cost.
FOC, or front-of-centre, is the percentage of the arrow’s weight sitting in the front half. Easton recommends 10–15% FOC for hunting setups and warns that going past roughly 20% weakens dynamic spine and can make the arrow nosedive at distance. More FOC is not automatically better; there is a window, and the makers publish it.
Buy a dozen, not a half-dozen
Arrows are consumable. You will lose some in the dirt, break some in a target, and pull some out with a bent nock. Buying twelve identical shafts from one production run means the arrow you shoot at a buck in November is the same as the ones you practised with in August. Buying six now and six next year means two batches that may not group together.
Number them
Write 1 to 12 on your shafts with a paint pen. Shoot them in order at a target for a few sessions and you will find the one that flies a fraction off — every dozen has one. Retire it to stump-shooting duty. This costs nothing and removes a real variable from your groups.
Then match the broadhead
Arrow and broadhead are one system, not two purchases. A heavier head shifts your FOC and your dynamic spine; a wide fixed blade demands more from your arrow’s straightness and your tuning than a mechanical does. Our broadhead roundup and the fixed vs mechanical comparison cover the other half of this decision.