Loads of shooters don’t have easy access to a 100-yard range. If they want to zero their rifle at 100 yards, but they can only shoot 25 yards, many shooters will sight in at that distance and assume that they’ll be OK at 100. But is that accurate?
Well, it can be, but it’s not as simple as “If you’re on at 25, you’ll be on at 100.” The theory behind that assumption is based on the fact that yes, a bullet’s trajectory does intersect with the scope’s line of sight at two different points—one close to the muzzle and one farther out. But assuming those two points are exactly 75 yards apart (25 yards out to 100 yards out) for your given rifle and load combination is just plain wishful thinking. The fact is that you might be close enough, but you might not.
The way to be more certain and make a 25-yard zero work for you is to use a ballistics calculator. You’ll need some information on your gun and your load for this. I actually like running this ballistics chart for every rifle and load combination I regularly hunt with, because I’m a numbers nerd and want to know my drop at various ranges so I always know how far I can confidently make a shot.
For the purposes of this article, I ran several different common bullets through Hornady’s ballistics calculator app (using the auto-filled rifle info, not inputting specific rifle details) and got the following data:
- A .270 100-gr. CX bullet sighted in dead-on at 25 yards should impact approximately 2.36 inches high at 100 yards.
- A 30-caliber 180-gr. CX bullet sighted in dead-on at 25 yards should impact approximately 2.46 inches high at 100 yards.
- A .22-caliber 75-gr. BTHP bullet sighted in dead-on at 25 yards should impact approximately 2.41 inches high at 100 yards.
- A 7mm 160-gr. CX bullet sighted dead-on at 25 yards should impact 2.48 inches high at 100 yards.
- And just for kicks, a 50-caliber 750-gr. AMAX sighted in dead-on at 25 yards (if that’s even a thing you would do) should impact 2.52 inches high at 100 yards.
It appears that across a wide range of calibers and bullet weights, if you sight in dead-on at 25 yards you’ll end up around 2.5 inches high at 100. In most cases, you’ll be dead-on again somewhere around 200 yards.
Now, the question of how bad it is to sight in at 25 yards and go shoot assuming you’re good at 100 yards depends on what you’re shooting. For hunting big game, most people would say you’re good to 100 or 200, and I would agree based on the size of the vital zone on big game. If you’re looking for more precision-type shooting or you’re trying to pick off squirrels at 80 yards, sighting in at 25 yards and trusting the ballistics chart isn’t going to get you dialed in as precisely as you want.
And notice I’ve used words like “should impact” and “trusting the charts.” Ballistics charts, especially if you’re using a 4DOF calculator, are pretty reliable, but you’ll never know for 100% certain if those numbers are exact for your rifle and your load and your conditions until you shoot the gun at 100 to confirm.
So the answer is yes, for hunting purposes, you can sight a gun in dead-on at 25 yards and know that you’ll be a couple of inches high at 100 and pretty close to dead-on at 200. To pull it off, you’ll need to input your specific rifle, scope and load data into a ballistics calculator and get exact numbers, and it’s always a good idea to shoot it at 100 to confirm that it’s doing what it’s supposed to be doing.
