Field Notes · v140 calibration anchor
Thirty-Five Down a Canyon
The wildebeest hunt taught me that three feet of drift at sixty yards isn't a shooter pulling left. The stag taught me the inverse — that when the math, the rig, and the shot all line up, the result is exactly what the calibration says it should be.
One was a failure. The other was the proof.
The shot
Red stag. About seven hundred pounds. Thirty-five yards. Quartering away, hard — not the gentle 15° off-broadside you'd take on a whitetail, more like a true 45° quartering presentation where you can barely see the offside shoulder. And the stag was below me, down a canyon, at roughly a 30° downhill angle.
That's the kind of shot most archers turn down. The internal path through that animal isn't 18 inches; it's closer to 28-30 inches of tissue, bone, lung, and the offside shoulder joint. A standard 100-grain field-tip-equivalent broadhead behind a 425-grain arrow has no business taking that shot. The arrow would stall against the offside scapula and you'd lose the animal.
This rig wasn't built for a standard shot.
The rig
Draw weight: 81 lb
Draw length: 28.5"
Let-off: 75%
Arrow: 460 grain total
Head: 100 gr BEAST mechanical, titanium ferrule
The whole build is anchored on one decision: a heavy titanium-ferrule mechanical with the kind of narrow cutting profile that opens reliably on impact but doesn't lose mass to the ferrule. Titanium ferrules are roughly half the density of stainless but with comparable yield strength — you spend the saved weight on blade length and broadhead diameter without giving up structural integrity. On a hard quartering-away shot through scapula bone, the ferrule has to survive intact for the blades to keep cutting on the way out.
460 grain at 81 lb is in the high-momentum range for a hunting setup. The Forge Score for this build on a quartering-away red stag scenario reads strongly because the momentum and the FOC are both in the band where the penetration math says the offside path is achievable. Not theoretical. Anchored against hunts like this one.
What happened
Full pass-through. Arrow entered behind the near-side rib, traversed both lungs at a downhill angle, exited through the offside shoulder. On the way through it shattered the offside leg joint — the kind of structural damage that drops an animal in seconds rather than letting it run.
The stag went about thirty yards and piled up. Clean recovery.
The shot most archers turn down is the shot this rig was built for.
What this anchors
This hunt is the empirical anchor for the Forge's shot-scenario × broadhead-type matrix. The matrix is the math that says: a 35-yard broadside shot and a 35-yard quartering-away + downhill shot are not the same shot, even on the same animal at the same range. The internal path is different. The bone presentation is different. The required penetration is different. And the broadhead that lets you take the second shot is not the same one that handles the first.
The matrix is calibrated against three documented hunts so far:
- Eland, 40 yards broadside, 500 gr / 15% FOC mech — almost-pass. Source for the Ashby reframe. The mech opened, the arrow stopped on the offside ribs. Lesson: on the largest game classes, mechanicals lose the penetration race even with massive arrow mass.
- Red stag, 35 yards quartering-away + 30° downhill, 460 gr / 100 gr BEAST Ti — full pen, offside joint shatter. This hunt. Lesson: titanium-ferrule mechs with narrow cutting profiles handle quartering shots through bone if the momentum is high enough to push the head through the offside scapula.
- Wildebeest, 60 yards broadside, 460 gr / 6° launch yaw — three feet of drift. Source for the yaw-to-drift coupling. Lesson: tune-quality dominates everything else; a cracked limb makes the matrix irrelevant.
The matrix is in the methods page §12. The Forge Score weights momentum at 25% and effective FOC (post-deflection-probability) at 20% — those weights are tuned against these hunts, not pulled from a textbook.
The non-trivial point
The reason this hunt matters isn't that I made the shot. The reason it matters is that the math said the shot was inside the envelope before I took it. The Forge Score on this rig for a quartering red stag at 35 yards was 89 — squarely in the Surgical band. That score is a prediction. The hunt validated the prediction. The score was honest about the envelope.
The wildebeest hunt validated the prediction in the opposite direction: the Forge Score collapses when the tune is bad, and the wildebeest hunt was the proof that the collapse was real. The stag is the mirror image — when the tune is clean and the build matches the scenario, the score holds and the shot lands.
This is what separates a calibrated tool from a calculator. A calculator gives you a number. A calibrated tool gives you a number that has been tested against the ground truth of a wounded animal recovered cleanly, or not. We log both.