When hunting in open country, your load needs to carry the energy that’s appropriate for the quarry as far away as you’re prepared to shoot.

Most conventional hunting ammunition is designed for optimum performance at about 100 yards. This is the average distance at which the great majority of all hunting shots is fired--as reported by countless surveys by numerous wildlife agencies--and therefore, it is the distance from the muzzle that most conventional hunting bullets are designed to achieve their peak efficiency at in terms of upset and expansion.

Hunting bullets are engineered to operate within a particular velocity window, depending on their caliber, weight, and construction. Below a certain "threshold velocity" they don't upset satisfactorily upon target impact. At excessive velocities, they may upset too rapidly and come apart or fragment after only shallow penetration, without retaining sufficient mass or energy to penetrate reliably into the quarry's vitals.

In general, most hunting rifle cartridges are loaded with bullets that enter their window of optimum velocity performance at around 100 yards from the muzzle. If you shoot an animal at extremely closer range, such a bullet may overexpand and fragment and not deal an immediate death blow. At distances beyond the limits of the optimum window, the bullet may upset only partially (or not at all), likewise not delivering immediate killing effect--particularly with an imperfectly placed hit.

You can get a rough rule-of-thumb indication of where the peak performance window actually lies for a particular bullet by looking at the information provided in the data pages of ammunition manufacturers' catalogs for the lowest velocity cartridge loaded with that bullet. These pages typically show data for "Short-Range Trajectory" (or "Average Trajectory") and "Long-Range Trajectory" with zero distances and trajectory profiles for shooting at different ranges.

The most common short-range zero is 100 yards, and the most common long-range zero is 200 yards, which is an indication that the peak performance window for most hunting bullets comes at velocities from 100 to 200 yards from the muzzle. You may find that same bullet loaded in higher-velocity cartridges with the same zero ranges on the data charts, but the lowest velocity loading is the one that gives you the best indication of its optimum performance window.

You can also use this information as a general indicator of the effective range of a particular cartridge loaded with that bullet. For example, the cataloged short-range zero for Remington's 150-grain SPCL .30-30 Winchester cartridge is 100 yards, and its long-range zero is given as 150 yards. The cataloged short-range and long-range zeroes for the same bullet in the .30-06 Springfield and the .300 Winchester Magnum are the same: 150 yards and 200 yards. This data can be interpreted to indicate that the slower-velocity 150-grain .30-30 finds its optimum performance window between 100 and 150 yards at 1,900 to 1,725 fps velocity, and that its effectiveness deteriorates past that. But does this also mean that if you shoot this same 150-grain bullet past 200 yards in a .30-06 or a .300 Win. Mag. its performance deteriorates at the same rate?

Not really. We need to look closer.

Applying The Rule
Everywhere we turn these days, we're bombarded with advertisements and magazine articles about "long-range" ammunition, "long-range" optics, and "long-range" rifles. Most hunting shots still come at close to medium ranges, and being able to make a long-range shot requires special personal preparation and circumstances. But if you're approaching a hunt where you think a truly long-range shot may present itself, the most important ammunition consideration is sufficient downrange energy. Even if your cartridge can deliver pinpoint accuracy at long range, it won't do you any good unless it delivers enough energy to let its bullet perform as designed once it gets there.