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Topic of interest: No. 7

Point Blank Range

A common belief, with roots back to old western movies and Cop shows, is that point blank range is an unspecified distance, very close to the muzzle of the gun, in which the shooter just can’t miss the target no matter where he aims. A more modern and useful definition is that point blank range of any gun is the maximum distance out to which the shooter can hold right on a game animal and be assured of a hit within a vital zone of the animal. It is a measure of how flat a gun will shoot. For varmints the vital zone may be 2 to 4 inches (+/- 2 inches) while for deer sized game the vital zone may measure 10 inches (+/- 5 inches) or more. Fig. 1 shows the vital area of deer sized game.

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Fig. 1- Vital zone of deer size animal

For example, let’s look at the trajectory for the .223 Remington, shooting a 55-gr. bullet with a muzzle velocity of 3,600 f.p.s. The bullet coefficient is 0.237. The scope-mounted rifle is zeroed for 200 yds. The end range is set at 400 yd. and the trajectory range increment is 20 yds. If we were trying to dispatch a varmint that had a kill zone of 4 inches and we were using the .223 Remington as sighted in Fig. 2, the bullet would be within the 4 inch span (+/- 2 inches) from the muzzle to about 250 yds.

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Fig 2-Trajectory for .223 Rem., zero at 200 yds.

 

However, we can improve on the maximum point blank range by setting our sight-in zero to a longer range. If we increase the sight-in zero to 250 yards you can see from Fig. 3 that the bullet will stay within the +/- 2-inch range from the muzzle to about 290 yards down range.

 

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Fig. 3- Trajectory for .223 Rem., zero at 250 yds

 

We were able to determine the maximum point blank range for the example by increasing the sight-in zero range, by trial and error, until the point blank range no longer fit the 4-inch span we allowed the bullet to deviate from the line of sight. Fortunately, with many of the ballistic programs now available there is no need to go through a trial and error procedure to determine maximum point blank range when this can be done by the computer in a few seconds. The Load From a Disk program advertised on this web site not only solves for the maximum point blank range, but also gives you the bullet impact at a standard range of 100 yards. Note from the example that the zero range for the maximum point blank range was 250 yards. Since most target ranges don’t have a target holder at 250 yards you can sight in your rifle to shoot 1.85 inches high at 100 yards to give you a 250 yard zero. The computer results are given as hard numbers so no trajectory interpretation is required. The only input values required are muzzle velocity, bullet BC and the vital zone dimensions (+/- 2.5-inches to +/- 5.0-inches).

Watch our web site for the next topic of interest "Shooting Sabots." Until then, shoot safely and know where your bullets are going.

Sincerely,
The Ballistician

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