As laser rangefinders came into being, and ballistic apps, precision rifles and riflescopes evolved to support longer-range shooting, dedicated riflemen delved deeper into ways to predict a bullet's path. Here's a look at several of the tools of the trade, tools that, properly used, will help you eliminate guesswork when shooting uphill and downhill.

But first, let's touch lightly on the basic physics of shooting downhill and uphill just to be sure that popular myths of the past are debunked, and that the forces that work on speeding projectiles are understood.

Shooting at angles is much misunderstood. Perhaps the biggest mistake many rifleman make is believing that the angle is greater than it actually is. This rifle is pointed at an 18-degree angle.
Many moons ago, it was popular to believe that when take shooting uphill, a bullet would hit high, and when shooting downhill, a bullet would shoot low. That notion has gone the way of iron sights. In truth, gravity exerts maximum influence on a traveling bullet when its path is level, perpendicular to the earth's pull.

When a bullet's path is angled high or low, gravity exerts more effect on velocity (which doesn't change a projectile's path appreciably) and less effect on its path. As a result, trajectory suffers less earthward "bend" and the bullet flies on a straighter path. The takeaway? Bullets hit high when shooting down and up.

Another tendency among shooters, even those of considerable skill, is to overestimate angles. I've seen lifelong old-school riflemen squint up a slope and proclaim, "That's steep... Say 30 degrees," when in reality, it's less than 15 degrees.

As precision rifles, optics, laser rangefinders, and other tools have increased the viable range of skilled riflemen, understanding of compensating for angles has increased, as have the tools necessary for accurately doing so.
Compensating when shooting downhill and uphill is a science, not voodoo, but you've got to have an accurate read on the angle for your compensation to be accurate. Angle can be measured many ways, ranging from scope-mounted gadgets, to smart-phone apps, to laser rangefinders that measure and display it. We'll take a closer look at various angle-estimating tools shortly.

Once you've measured the angle, you've got to calculate how much that angle will affect your bullets' point of impact.