Mountain Shootin'

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Slope effect on trajectory diagram
Slope effect on trajectory diagram

Q: I do a lot of missing when shooting uphill and downhill. I just can't seem to work out where to hold on the game. Shooting uphill I figure the bullet will land a bit lower, so I hold a bit higher - and that's where the bullet lands. Shooting downhill I thought the bullet would hit higher and so hold bit lower and still miss the durn animal. What am I doing wrong? Help!
Albert Murley

A: The inescapable law of in flight ballistics is that the bullet always rises above the line of sight whether you shoot an angle above or below a horizontally zeroed rifle. The greater the degree of angle, the greater the amount of rise. Not only that, but the amount of rise is the same both for uphill and downhill shooting, provided that the amount of angle away from the horizontal is the same. Gravity is the operational factor, but it is not the pull of gravity that's important - it's the angle of the

Downhill shooting - credit Ron Spomer Outdoors
Downhill shooting - credit Ron Spomer Outdoors

bullet's path measured against the line of gravity. The line of gravity is vertical, so whether you elevate the muzzle of your gun by "X" degrees or depress the muzzle by "X" degrees, you are changing the angle of the bullet's trajectory respective to the line of gravity by the same "X" amount. The effect of a change of uphill or downhill angle on the bullet's flight path is therefore the same. Most hunters instinctively aim higher when compensating for an uphill or downhill shot and decide where to aim based on their estimate of range or what their rangefinder tells them the distance is. Today's modern crop of laser rangefinders will calculate the hillside factor for you. Alas, my old Leica doesn't. 

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