July 25th, 2021
Our Shooters’ Forum was abuzz about a range threatened with closure due to rifle over-shoots hitting a farm two miles away from the firing line. One reader was skeptical and asked “How is that possible? Were these guys aiming for the stars?” You may be surprised. A rifle doesn’t need to be angled up for a bullet to land at a distance of miles. It is important that hunters and target shooters aim their barrels in a safe direction. A small tilt of the barrel (above horizontally) can change a bullet’s trajectory.
How many degrees of muzzle elevation would it take to hit a barn from 3000 yards? Ten Degrees? Twenty Degrees? The answer is actually much lower — for a typical hunting cartridge five to seven degrees of upward-angle on rifle is enough to create an trajectory that will have your bullet impacting at three thousand yards — that’s about 1.7 miles!
Five degrees isn’t much. Take a look at the diagram. The angle displayed for the up-tilted rifle actually is 5.07 degrees (above horizontal). We calculated 5.07 using JBM Ballistics. The angle that would produce a 3000-yard impact using a 185gr.30-caliber bullet fired at 2850 fps.MV. This would be a moderate “bookload” for a.300 WinMag deer rifle.
Here’s how we calculated the angle value. Litz-derived BCs were used to calculate the angle value for a 185gr Berger Hunting VLD that was launched at 2850 feet per second. The drop at 3000 yard is 304.1 MOA (Minutes Of Angle), assuming a 100-yard zero. This was calculated using the G7 BC and the JBM Ballistics Program. 60 MOA are required for every 1 degree Angle. Thus, 304.1 MOA equals 5.068 degrees. This means that your 185gr bullet (2850 FPS MV) will impact 3000 feet down-range if you tilt your muzzle slightly more than five degrees.
Figures of Trajectories for Different Bullets and MSs. If the bullet travels slower or you shoot a bullet that has a lower BC, then the angle required for a 3000-yard impact will go up. However, the principle is the exact same. Let’s assume you have a 168gr HPBT MatchKing that is launched at 2750fps MV from an.308 Winchester. This is a typical tactical load. The total drop at 100 yards is 440.1 MOA or 7.335 degrees. This is a higher up-tilt than the example above, but it’s still not too much when you consider how a rifle might have been handled during a negligent firing.
Imagine a hunter getting in position for a prone shot. He could accidentally touch the trigger with a muzzle angle of more than 10 degrees if he is not careful. Even shooting from a bench, it is possible to discharge a rifle before the gun has been levelled. This could send the shot over the Berm and potentially thousands of yards downrange.
This article should have shown you that even a small amount of barrel elevation can make all the difference in your bullet’s trajectory and landing position. No one wants to cause injury or put holes in the homes of distant neighbors.
Let’s return to the original example of a bullet weighing 185gr and traveling at 2850 fps. JBM says that the projectile will still travel 687 fps at 3000 meters, with 193.7 ft/lbs retained energy. This is more than enough energy for a deadly strike.
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Tags: Barrel Tilt, Gun Safety, Level Muzzle, Long Range Impact, Negligent Discharge
