A great range activity is sighting in that new hunting rifle before the hunting season opens. Iron sights or scopes the sights, gun and ammunition need to work in harmony to ensure clean and humane hits on game. Most of us don’t shoot our rifles much out of season but we need to ensure that our sights are on with no deviation from before. Change in ammo? Every loading has unique characteristics, factory or hand loads. You need to ensure your hits are placed in accordance with your sights.
Deer & Game Kill Zone
We all are aware that the bullet trajectory is an arch, not a straight line so we need to align our sights at range and get a zero to compensate for longer or shorter ranges. All game has a kill zone. If a bullet hits within the circle of the kill zone it should be a mortal shot. One way is to determine the maximum point blank range (MPBR) to ensure kills at all practical ranges. From the muzzle to the maximum range of a 10” kill zone and the maximum point blank range, will allow the bullet path to rise above the line of sight 5” and drop below the line of sight 5”. Example: take a 7mm Remington Magnum 160 grain bullet. At a 10” kill zone and the rifle sighted to 310 yards you should put a round into the kill zone if you aim for the center of the circle and hit from the muzzle out to 367 yards. The typical deer represents about a 6” kill zone. Sight in at 254 yards with a rise of 3” above the line of sight and a drop of 3” means you can reach out 300 yards and keep within the kill zone.
Maximum Point Blank Range (MPBR) Shooters Ballistic Calculator
It takes a ballistics calculator with a MPBR calculation point to determine ranges. We need to be able to calculate the MPBR from trajectory data and have the program give us the MPBR.
Point one: Use a conservative kill zone for the game you are hunting.
Point two: Assume a full size kill zone but shoot with 15% of the MPBR zero distance.
Bore sight the weapon. With a bolt action you can do the poor man’s sighting procedure. Look down the barrel on a bench rested gun and adjust until the cross lines of the target set at a 100 yards are centered with the bore. Adjust the sight or scope to center on this spot as well. You are now bore sighted at 100 yards. Now shoot a three-shot group. Practical hunting will seldom encounter a situation where you can get off more than 3 shots. For accuracy and precision studies you would want a minimum of 5 shot and preferably 10 shot string to build a statistical model. But for hunting 3 shots should suffice. Remember that 1” at 100 yards is about 1 minute of angle (MOA). If the center of your grouping is low a 1 ½ and right 1” you can adjust to center. Given most scopes are 1/8 MOA or ¼ MOA per click you now adjust your scope. With ¼ MOA per click you would raise 6 clicks and move left 4 clicks. Shoot for confirmation another 3 shot string from a cold barrel. In the field you seldom ever shoot a first shot from a hot barrel. Give the at least a 15-minute cool down between shot groups. You should be able to sight-in with under 9-12 rounds fired.