The Rifle Zero

John Begakis engages long-range rifle steel during the 2010 3-Gun Nation Championship in Las Vegas.

By Bryce M. Towsley (www.brycetowsley.com) 

In 3-gun, the rifle has by far the widest spectrum of target distances to deal with. Take, for example, Stage 5 at the recent Superstition Mountain Mystery 3-Gun match. The first rifle target was inches from the muzzle and the stage ended with shooting at steel targets at 300 yards.

With the AR-15 rifle dominating this sport, there are some unique challenges for both close and far targets. Because of the rifle’s design the sights must be set high above the line of the bore, which causes changes in the bullet’s path relative to the line of sight. To shoot well, you must be aware of the offset and how it affects the bullet’s impact, particularly at close range.

Many of the top shooters I know use a 200-yard zero for their rifles, because it works best over a wide spectrum of distances. But, they stress that you must know where your rifle will hit at every single distance.

My gear is fairly typical of what most shooters use. It’s a JP Enterprises JP-15 rifle with Swarovski Z6 1-6X scope. The optical center of the scope is about 2.75 inches above the center of the rifle’s bore. I use Federal Premium .223 Remington ammo, with 55-grain Ballistic Tip bullets, which exits the 18-inch barrel at about 3,000 fps.

With a 200-yard zero the bullet impacts 2.22 inches low at 10 yards. So for that tricky A-zone shot, hold on the top. At 25 yards it is 1.42 inches low. At 50 yards, it’s only .31-inch low.  At 75 yards, it’s .54-inch high and at 100 it’s 1.09-inch high. At 130 yards it peaks at 1.35 inches high.  After 200 yards the bullet will always strike low.  At 250 yards it will be 2.87 inches low; at 300 yards, 7.59 inches low.  With a 350-yard target it will be 14.46 inches below the line of sight and at 400 its 23.82 inches low.  At 500 it is 51.79 inches low. 

With any target past 300 yards or so you will be much better off to use a multiple aiming point ballistic reticle like Swarovski’s BTR reticle, or dial in the offsets. Don’t forget changes in altitude will affect the point of impact (This data is from sea level.). The only way to be sure is to shoot your rifle at every distance and write down the results in a notebook.

Or, if you shoot in Tactical Optics, don’t bother. That’s my division and the less competition I need to deal with, the better my chances!

Posted on 4/8/2011