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Calculating Load Data to Shoot Big Game Point Blank at Sea Level & High Elevations

Point blank is the range at which you zero your gun to hit within the target or kill zone of the game with a direct point of aim. Take the mule deer. A “muley” is a fairly large critter with a kill zone about 10-11 inches in diameter centered just behind the front shoulder and linear center line of the body. This would mean that if your bullet trajectory can rise above the line of sight 5.5 inches and drops 5.5 inches below it, the bullet will impact into the kill zone for a quick and humane kill on the game. If the game is within the point-blank range, it will hit in the target area or kill zone. But how do you arrive at the point-blank sighting and range and what is minimum and maximum ranges you can use the data. Well let’s take a look.

Elk & Deer Kill Zone

The Hornady GMX bullet is a solid copper bullet with a plastic ballistic tip. Being a non-lead containing projectile, it is legal wherever rifle hunting is allowed, even in the sovereign Republic of California. The point-blank range for the 165 grain GMX and 180 grain GMX fired at 2700 ft per second is very similar. The 165 grain in a 308 Winchester or the 180 grain in a 30-06 Springfield. The 30-06 handles heavier bullets better than the 308 Winchester, making the old ’06 a bit more versatile and allowing the same zero for mule and white tail deer while still effective on elk. Jack O’Connor in his book the Hunting Rifle offers the kill zone for deer and elk as follows:
• Small deer = 8.5″-9″
• Medium size deer = 10″-11″
• Large deer = 11″-12″
• Elk = 14.5″-15.5″

Fall is the Big Game Hunting Season

These species comprise that the majority of the hunting that occurs in the fall throughout the US. An inexpensive target for sighting in and one that covers the smaller target area in just plain old 9-inch paper plates. If you’re good enough to hit a 9-inch diameter target area you good to go on most everything else. The specs are 2700 fps with the hunt occurring at 5000 feet above sea level at 60 degrees Fahrenheit at 50% relative humidity.
• GMX 165 grain, Ballistic Coefficient: (G1) 0.447 loaded into a 308 Winchester @ 2700 fps
• GMX 180 grain, Ballistic Coefficient: (G1) 0.485 loaded into a 30-06 Springfield @ 2700 fps
Tools:
• Hornady Handbook of Cartridge Reloading 10th Edition.
• Point Blank Calculator: http://www.shooterscalculator.com/point-blank-range
• Mean Pressure at Altitude calculator, for those who want to calculate correction for atmospheric conditions: http://www.calctool.org/CALC/phys/default/pres_at_alt

Hunting at Sea Level Elevation

:
Drag Function: G1 International Standard Atmosphere
Bullet: Hornady GMX 180 grain Altitude: Sea Level (0 ft)
Ballistic Coefficient: 0.485 Barometric Pressure: 29.92 Hg (inches of Mercury)
Muzzle Velocity: 2700 fps Temperature: 59 degrees Fahrenheit
Sight Height above bore center: 1.5 inches Relative Humidity: 50%
Target zone size: 10 inches Speed of Sound: 1116 fps
Near Zero: 19 Yards
Far Zero: 279 Yards
Minimum PBR Range: 0 Yards
Maximum PBR Range: 329 Yards
Sight-in at 100 Yards: 4.17 inches high

Shooting at High Elevations

This is corrected to 5000 ft above sea level:
Corrected For Atmosphere
Drag Function: G1 Adjusted BC: 0.7
Bullet: Hornady GMX 180 grain Altitude: 5000 ft
Ballistic Coefficient: 0.485 Barometric Pressure: 24.07 Hg (inches of Mercury)
Muzzle Velocity: 2700 fps Temperature:60 degrees Fahrenheit
Sight Height above bore center: 1.5 inches Relative Humidity: 50%
Target zone size: 10 inches Speed of Sound: 1117 fps
Near Zero: 19 Yards
Far Zero: 287 Yards
Minimum PBR Range: 0 Yards
Maximum PBR Range: 340 Yards
Sight-in at 100 Yards: 4.11 inches high

165 Grain GMX Loaded into a 308 Winchester Load Data

For reference we will compare the 165 grain GMX loaded into a 308 Winchester:
Drag Function: G1 International Standard Atmosphere
Bullet: Hornady GMX 165 grain Altitude: Sea Level (0 ft)
Ballistic Coefficient: 0.447 Barometric Pressure: 29.92 Hg (inches of Mercury)
Muzzle Velocity: 2700 fps Temperature: 59 degrees Fahrenheit
Sight Height above bore center: 1.5 inches Relative Humidity: 50%
Target zone size: 10 inches Speed of Sound: 1116 fps
Near Zero: 19 Yards
Far Zero: 276 Yards
Minimum PBR Range: 0 Yards
Maximum PBR Range: 326 Yards
Sight-in at 100 Yards: 4.18 inches high

Calculating Point Blank

Not much different, so you could set the zero essentially the same for both bullets at same point. So, your 308 Winchester and that 30-06 should shoot to nearly the same point-blank range. Point-blank ranging simplifies targeting, with little time to react allowing you can put a round into the kill zone of a game animal and not have to compensate for the range. You won’t have time to calculate for accuracy because of the fluidity of most game hunting opportunities. These bullets and specs are for presentation only you will have to calculate for your rifle, cartridge and conditions.

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