137 feet of bullet drop is like shooting a mortar.
"That's because long shots generally go places you wouldn't wanna have to go afterwords to have to confirm 'em. Confirmation's a desk pogue's problem. You know what it takes to make a shot at that range? Everything comes into play that far. Humidity elevation, temp, winds, spin-drift. There's a 6-10 second flight time so you have to shoot it where the targets going to be. Even the coriolis effect, the spin of the earth comes into play."
-Bob Lee Swagger
I used to have an 1880s 45-70 Springfield manual that had fold-outs in the back. They were "killing range" diagrams of standing men and men on horseback. One specific "killing range" with the 500 grain infantry load was the distance between being hit in the head and hit in the ankle at 1,000 yards. That lethal distance was something like 20 yards, so if you were off by just 20 yards in range estimation either way, you'd miss.
Makes this guy's shot all the more remarkable, even though he admitted it was a "scratch shot".