This simple sight-in system does away with the need to compensate for a bullet’s arc at all but extreme ranges.
Advanced reticle systems in today’s scopes are a great method for pinpointing targets at a variety of long ranges. But multiple crosshairs, hash marks, mil dots and numbers can get confusing, particularly when you’re hyperventilating as the biggest buck of your life is walking away. You have to shoot NOW. Do you have the mental control to select the correct crosshair?
There’s a simpler system, one that requires no confusing arrays, no mathematical calculations and no stress. Just aim at the center of the animal’s vital zone and concentrate on a clean trigger break. From 1 to as far as 300, perhaps 400 yards, you’ll hit the vitals.
Welcome to the wonderfully simple world of Maximum Point-Blank Range, or MPBR.
Anyone familiar with crime movies, books or news reports knows that shooting anything at point-blank range means you can’t miss. “The victim was shot at point-blank range.”
So what is this magical PBR? Ten feet? Twenty? The muzzle touching the victim? No one knows because the term has never been defined. Maximum Point-Blank Range, however, has.
MPBR is the distance over which a shooter can hold his sights dead on the center of the target and hit it. The bullet may strike the upper or lower edge or any point in between, but it will not miss. To the surprise of many, with the right cartridge, bullet and target, this can stretch well past 400 yards.
Here’s how it works: Every bullet fired — from any rifle — begins to be pulled to earth by gravity as soon as it leaves the barrel. In order to make it shoot above the point of aim (POA) at 100 yards, the sights are aligned so that the barrel tilts slightly upward. The bullet then departs at an angle that puts it through and above the line-of-sight (LOS), much like throwing a baseball from centerfield to homeplate. You look at homeplate, but arc the ball high in order to compensate for gravity pulling it down.
Because bullets depart much faster than baseballs and resist air drag much better, they don’t need to be angled nearly so drastically high in order to shoot what we call “flat” to 200 or 300 yards.
This does not mean that bullets rise after they leave a barrel. That’s a myth that developed from a misunderstanding. When shooters learn that their bullets strike higher than they are aiming at 100 yards, then fall onto the POA at roughly 240 yards, they assume the bullet climbed after leaving the muzzle. In reality, it was merely aimed at that slight upward angle. (It would take a propulsion force, i.e. a rocket engine, to make a projectile rise above its initial line of launch.)
But, because we can intentionally angle a barrel to throw its bullet above LOS, it is possible to select just how far above that line we wish the projectile to travel. The greater the angle of the muzzle in relation to the LOS, the higher above POA the bullet will fly and the farther it will travel before gravity pulls it down through the LOS again, thus increasing MPBR.
A convenient way of visualizing this is to think of shooting down the center of a long pipe. Adjust your sights so that your bullet just misses the inside top of the tube at the peak of its trajectory. From that point it will gradually fall until it hits the bottom of the pipe far downrange. That striking point is your MPBR. With a .22 Long Rifle, it could be 85 yards. With a .22-250, it could be 300 yards.
Target size is critical to determining this distance. The bigger the vertical vital zone, the longer the MPBR for any cartridge/bullet combination. The chest of a coyote is roughly 8 inches top to bottom. A mule deer’s chest might measure closer to 14 inches, a moose 30 inches. MPBR will be significantly farther for the larger vital zones.
Determining MPBR for any particular rifle/cartridge/bullet begins by selecting a vital zone diameter. Let’s say we’re setting up for an average-size whitetail with a 14-inch vital zone. At its top is the spine, at its bottom the heart. If we hold exactly dead center, our bullet can hit as high as 7 inches above the aim at any point along its travel and we won’t miss!
But that doesn’t take into account natural bullet dispersal. If our rifle normally groups five shots inside a 1-inch circle (1 MOA), it can throw any bullet a half-inch higher than the average center of the group at 100 yards, 2 inches at 200 yards and so on.
Shooter error can easily add another inch or two of vertical error, resulting in overshooting the target by several inches at mid- to long ranges.
Few of us shoot any rifle at MOA in the field. Thus, it’s wise to downgrade vital zones to compensate. A more realistic target of 10 inches is a safer bet for setting MPBR for deer. So let’s set our sights to strike no higher than 5 inches above LOS for deer. For coyotes we’d be safe with 2 inches.
Determining MPBR is done most easily by consulting ballistic charts in handloading manuals or on various websites.
Increasing initial velocity greatly increases MPBR. This is a significant benefit of magnum cartridges. Increasing bullet BC also increases MPBR. For the longest MPBR, choose the fastest cartridge you can shoot accurately and the highest-BC bullet that will deliver the terminal performance needed for your game.
MPBR can also be determined via trial and error on the range by punching paper targets and measuring the range of the highest hit and the extreme distance when the bullet falls below your chosen vital zone. Even if you set things up using ballistic charts, check them on paper. Not every rifle and bullet performs exactly the same. Also, spend considerable time shooting a variety of long-range targets from simulated hunting positions to determine whether your chosen vital zone diameter is excessive. You may need to settle for a maximum trajectory of 4 inches or 3 inches instead of 5 inches for deer.
With MPBR set, memorized and practiced, you should be confident of hitting game without worrying about precise range until its extreme, i.e. beyond 300 yards. You needn’t ever worry about “hold under” again, and rarely “hold over.” Aim for center and if the first shot misses, stalk closer next time. If your quarry remains standing in the clear and you have a solid rest, aim just over the backline for your second shot. The vast percentage of times, you should get first-round hits and one-shot kills.
This article was published in the July 2008 edition of Buckmasters GunHunter Magazine. Subscribe today to have GunHunter delivered to your home.