Arrow setup analysis for a 30-inch arrow at 320 fps. Default specs: 398 gr arrow, 8.4 mm shaft diameter.
Total arrow mass for a 30" build: 398 gr = 255 gr shaft (8.5 GPI × 30") + 143 gr components (point + insert + nock + fletching).
KE: 90.5 ft·lbf — Momentum: 0.565 slug·ft/s
| Distance | Velocity | KE (ft·lbf) | Momentum (slug) |
|---|---|---|---|
| 0 yd | 320.0 fps | 90.5 ft·lbf | 0.565 |
| 10 yd | 314.3 fps | 87.3 ft·lbf | 0.555 |
| 20 yd | 308.7 fps | 84.2 ft·lbf | 0.545 |
| 30 yd | 303.1 fps | 81.2 ft·lbf | 0.536 |
| 40 yd | 297.7 fps | 78.3 ft·lbf | 0.526 |
| 50 yd | 292.4 fps | 75.6 ft·lbf | 0.517 |
This build pairs a slightly long cut with a high-speed compound launch. At 30 inches the shaft is suited to longer draw lengths, adding a touch of forward weight and a calmer, more stable flight, and 320 fps is the kind of speed produced by aggressive, high-let-off compounds built for flat trajectories and short reaction windows. Together they finish at about 398 grains, which is what drives the kinetic energy and momentum figures in the table above.
Because this is a slightly long cut, the extra column length weakens the dynamic spine slightly, so a marginally stiffer shaft often tunes best. The launch matters too: with a high-speed compound launch, the dynamic-spine reaction is dominated by spine and rest tuning, because fast cams expose the smallest paper-tear and broadhead-flight errors. Pick a static spine that lands stiff once this 30" shaft and your point weight are factored in, then confirm it with bare-shaft or paper tuning.
At roughly 90.5 ft·lbf this is elk-class kinetic energy — this reaches elk-class energy, the territory recommended for elk, moose, and other heavy big game where maximum penetration is the priority. Keep in mind that a slightly long cut at 320 fps is only the starting point; broadhead choice and shot placement still decide the outcome more than the headline energy number.
A high-speed compound launch pushing roughly 398 grains yields about 0.565 slug·ft/s of momentum. That is heavy penetration potential: this is heavy-penetration momentum, the kind that drives through rib bone and dense muscle and resists deflection on angled shots. Momentum, more than raw kinetic energy, predicts how a 30" arrow holds up against bone and angled entry.
For a slightly long cut launched at 320 fps, dial in rest centre-shot and timing first, then verify broadhead flight against field points at distance. Spine and rest tuning, because fast cams expose the smallest paper-tear and broadhead-flight errors — so re-check the tear any time you change point weight, since that shifts the dynamic spine on a 30" shaft more than most archers expect.