What arrow spine for 40 lb draw at a 27 inch arrow
The starting spine for a 40 lb draw at a 27 inch arrow with a 100 grain point, and the weight floor.
Dry-fire warning
Crossbow bolt data and archery arrow spine, nock and thread data are quoted from each manufacturer's published figures, owner documentation and industry standards, cited on every page. A nock, spine or grain-weight mismatch can cause a dry-fire that damages the bow and can injure the shooter. Confirm against your own owner's manual and the arrow maker's own chart before shooting, and never drop below the stated minimum total weight.
| Draw weight | 40 lb |
|---|---|
| Arrow length | 27 in (cut, nock groove to shaft end) |
| Point weight | 100 gr |
| Recommended spine | 600 (published band 500-600) |
| Minimum total weight | 200 gr, from the 5-grains-per-pound floor |
Easton 5mm Axis carbon arrow shaft (600 spine)
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A 40 lb bow with a short 27 inch arrow flexes the shaft little, so it takes a weaker 600 spine. This is the light end of the widely published 500 to 600 band for 25 to 45 pounds.
Spine is a starting point, not a guarantee, because a 340 from one brand can differ from another. Confirm on your arrow maker's chart at 27 inches and 40 pounds, or bare-shaft test before cutting a dozen.
Whatever spine you land on, keep the finished arrow at or above 200 grains total, the 5-grains-per-pound floor, so the bow is not shooting dangerously light.
The rules behind this pick
Sources: Nock On Archery - Arrow Spine Chart: choosing the correct spine · Sportsman's Warehouse - Arrow Spine Charts: Compound, Recurve and Traditional