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The .17 Winchester Super Magnum...A Big Leap Forward in Rimfire Ballistics

January 6, 2014
Bill Waugaman , Ohio Valley Outdoors

Three factors affect a bullet trajectory once it leaves the barrel...gravity, cross wind and wind resistance. Gravity is the constant force causing bullet drop and it is the same for any bullet whether it's a 20 grain .17 or a 750 grain .50. Cross winds cause horizontal bullet drift to the left or right; the amount of drift is determined by wind speed and direction of wind with respect to a bullets path. Wind resistance slows the forward movement of a bullet; humidity, barometric pressure and air temperature come into play.

Bullet shape (ballistic coefficient) and velocity are two ways a manufacturer can minimize the effect these three factors have on bullet trajectory. The ballistic coefficient of a bullet (a function of mass, diameter and drag) is the ability to overcome air resistance while in flight. The higher the ballistic coefficient, the better the bullet will retain down range velocity and trajectory. This brings us to the subject of bullet velocity since trajectory becomes a function of time.

Simplified, the longer it takes a bullet to get from Point A to Point B, the more it will be effected by all three factors mentioned previously. With the introduction of Winchester's new .17 Winchester Super Magnum, there is now a rimfire cartridge with a muzzle velocity of 3,000 fps. In comparison to a .17HMR (20 gr. at 2,375 fps) or a .22WMR (30 gr. at 2250 fps), the ballistics of this new rimfire cartridge are impressive. The four graphs show how these three cartridges are affected out to 200 yards by gravity (bullet drop), cross winds (bullet drift) and wind resistance (downrange bullet velocity). The fourth graph shows bullet energy...a function of bullet weight and velocity.

Article Photos

Velocity vs. Range

When the .17HMR was introduced, it broke new ground for rimfire cartridges (2,500+ fps) and became a success almost overnight with its impressive ballistics. Based on the ballistic graphs shown, the new 3,000 fps .17WSM will take rimfire cartridges to a new level of performance.

** Graphs courtesy of Winchester Ammunition.

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