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Hunting highlights – September 2024
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Zeroing your rifle for big game hunting

By WDFW staff

A key task in preparing to hunt with a modern firearm is zeroing, or adjusting the sights so you can predict where your bullet will hit at a given distance. If your rifle isn’t zeroed or if you don’t know your zero, then you can’t guarantee that you’ll kill game cleanly and ethically.

What’s a zero and why does it matter?
The idea is to keep the bullet’s point of impact (POI) very close to where you aim (point of aim (POA).

The line from your eye to the target is called the line of sight. Zeroing brings the path of the bullet (line of flight or trajectory) very close to the line of sight. The two lines will never match exactly because the line of sight is straight and the line of flight is the bullet’s trajectory curve that gets steeper as distance increases.

When a rifle is zeroed, the line of flight will cross the line of sight 20-30 yards from the muzzle, travel above the line of sight for some distance, then cross the line of sight again and drop below it. The greatest distance between these two lines is called the maximum ordinate—a very important number. The maximum ordinate and the exact distances at which these lines cross depend on the speed and shape of the bullet. So does the amount the bullet drops below the line of sight as distance grows.

You can find figures for maximum ordinate, bullet drop, wind drift, etc., in reloading manuals, ammo maker’s websites, and online ballistic calculators like the one  on Federal Ammunition’s website.

Getting a zero isn’t difficult
Rifles don’t come from the factory already zeroed. There are several methods to zero a firearm, all of which are usable once you understand them. The key is to match the zero to the game animals and the conditions where you intend to hunt, and keeping the maximum ordinate less than ½ of the size of the game’s vital zone. In other words, the goal is to ensure that the bullet’s highest point (maximum ordinate) is less than half the size of the animal’s vital zone. This minimizes the risk of missing the vital area due to the bullet’s arc.

Zeroing for open country
Much of eastern Washington is open country, where shots can be several hundred yards. A maximum ordinate of three to four inches will keep the bullet in the vital zone of most big-game species for almost all ethical hunting distances.

For rifles with a muzzle velocity over about 2,500 feet per second (fps), zero so the bullet hits 3” high at 100 yards. Line of sight and line of flight will cross at about 25 yards and again just beyond 200 yards, and the trajectory should be flat enough to keep your shot within the vital zone out to about 275 yards. For rifles with a muzzle velocity between about 2,000 and 2,500 fps, the same +3” POI at 100 yards will have the bullet crossing the line of sight around 175 yards and dropping below it a bit past 200.

If your rifle’s muzzle velocity is below about 2,000 fps, then zero for 100 yards and pass up longer shots. From an ethics perspective, no matter what the muzzle velocity, you should strongly reconsider shots past the point where the bullet strikes below the vital zone.

Zeroing for brush hunting
Much of Washington is covered in dense forest where hunters may need to shoot through small gaps in the brush. Shots are short, so there’s no need to worry about hitting at longer range. If your rifle has a muzzle velocity greater than 2,000 fps, then zeroing for 125 or 150 yards will keep your maximum ordinate low, making it easier to shoot through gaps in the brush.

Zeroing for commercial timber properties and tree farms
Hunters on large timber company lands and tree farms can experience a variety of habitats ranging from dense brush to wide-open clearcuts. A maximum ordinate of one to two inches is a good compromise. This is a 200-yard zero with most modern, high-velocity cartridges, and it keeps the bullet in the vital zone to about 250 yards.

Zeroing handguns
With iron sights, a zero that puts the bullet about an inch above POA at 25 yards usually puts it just below POA at 50, which is a good maximum range for most shooters. Scopes and other optical sights can extend this range a bit, but hunters should remember that handguns are less powerful than rifles—they can run out of power at short range even when the trajectory is relatively flat.

Zeroing shotguns
Different loads can have wildly different POI and group sizes even in the same gun. Shotgunners should test POI, pattern, and group size of various loads before the season, then buy enough of the best load for practice and for the hunting season.

Buckshot and slugs are usable for big-game hunting to about 25 yards in most guns with bead sights. Here, the hunter doesn’t zero as with a rifle, but should shoot enough to understand where the gun is likely to hit.

The few buckshot loads that pattern well enough for big game hunting benefit greatly from rifle-type sights zeroed at 25 yards. In smoothbore guns that shoot slugs well, sights can extend range enough to benefit from a 50- or 75-yard zero. Rifled barrels and sabot ammunition can reach even farther; zeroing at 75 or 100 yards works for them.

Zeroing muzzleloaders
Trajectory for muzzleloaders varies based on whether you’re using a round ball or conical bullet. As always, match your zero to the bullet’s trajectory, the game you hunt, and the conditions under which you expect to hunt.

Before you begin, ensure all scope mounting screws are set evenly and to the manufacturers recommended tightness. (WDFW/Tom Ryle)

This shooter is making adjustments after shooting several rounds from a solid rest. (WDFW/Tom Ryle)

Having another person watch the target through a spotting scope is very helpful to see the point of impact for each shot. (WDFW/Tom Ryle)

Using masking tape to cover holes in a target will make it easier to evaluate shot placement between adjustments. (WDFW/Tom Ryle)

Advanced topics

Zeroing for longer shots
Many hunters want to take game at long ranges. This takes a rifle that’s accurate and powerful, precise wind meters and rangefinders, scopes with rugged internal adjustments, deep study of the problems of long-range shooting, and solid training. Even then, the skills required to make long shots under pressure fade quickly without constant practice and carefully matched rifle and ammunition. It can take hours to reach a cleanly killed animal over several hundred yards of rugged terrain. In that time, the meat could spoil or you could end up field-dressing and recovering it after dark. Wounded animals have a significant head start over the hunter, who can expect a difficult tracking job. So, no matter how good your equipment and skill are, shooting at game beyond about 250 yards is rarely a good idea.

That said, the question of zero remains. The answer depends on whether you plan to dial elevation for each shot or use an aiming point built into the reticle to hold over the target.

To dial elevation, start by zeroing for maximum point blank range (MPBR)—long shots only come in open country but plenty of game there is still taken within 200 yards. (Zeroing for distances beyond MPBR can increase maximum ordinate so much that you shoot completely over game on quick shots at more typical ranges.) Then learn your drops and confirm them at long range. Write them on a piece of paper taped to your stock or scope, then dial for longer shots as needed.

Holding over uses reticles calibrated for a specific load under specific atmospheric conditions that may not exist where you hunt. Zero as the scope manufacturer recommends, then establish a baseline for your ammunition and rifle by shooting them to determine the differences between their recommendations and what works in the real world. Then test everything to the longest distance you plan to shoot.

Mastering either method takes time. Start early in the year so you’ll be ready on opening day.

Zero your rifle now

Don’t wait for “hunter sight-in day” — ranges are typically crowded in the weeks before the season and range staff may not have time to help you or answer questions in detail.

Before you go:

  • Check the screws on your rifle (action screws, screws in the rings and bases, etc.) and for proper torque. This will usually decrease group size, but changing the torque after you zero will usually alter POI
  • Measure your muzzle velocity with a chronograph or determine what velocity the factory claims, then match the type of zero you plan to use to the type of country where you’ll hunt
  • Use a ballistic calculator to determine your desired point of impact at 25, 100, and 200 yards
  • Gather the things you’ll need—ranges may not sell them
    • Eye and ear protection
    • Two boxes of the same ammunition you intend to use on your hunt, since other loads will likely have different POI. You may need more than one box if problems arise
    • Targets with a grid pattern printed on the paper, which simplifies making sight changes
    • Any tools (small screwdriver, hex-head wrenches, etc.) needed to adjust your scope or sights

At the Range

  • Pick a range with solid benches and a padded rest. Try to zero on a day with little or no wind
  • Hang a target at 25 yards
  • Fire a three-shot group
  • Note the distance from the center of the group to the POI determined from the ballistic calculator
  • Change your sights to move the group to the desired POI
    • On a scope, the dials are marked with the direction and distance that each click will move the sight at 100 yards. Divide that distance by 4 to find the amount of movement at 25 yards
    • Peep sights and open sights are usually not marked with either distance or direction. Make a pencil mark on the sight to show where it was before you moved it, then move the sight, fire another group, note the distance the group moved, and adjust from there
  • Let your barrel cool between groups until you can comfortably touch it with your bare hand. A hot barrel may not have the same POI as a cool barrel, and heat rising from it can make it hard to see your target clearly
  • Once POI and POA are the same at 25 yards, move your target to 100 yards
  • Fire another three-shot group to POI. Let your barrel cool again
  • Continue to adjust the POI until it’s where you want it
  • Hang a target at 200 yards if your range permits, then confirm your 200-yard POI

The steps for zeroing a handgun are the same as for rifles but the distances are shorter. Start at 10 or 15 yards and work out from there.

Once any weapon is zeroed, you should check it periodically to ensure that the zero hasn’t shifted. Things that can shift your zero include:

  • Changes in humidity, which can cause a wooden stock to warp slightly
  • Changing ammunition to a different type, brand, or bullet weight
  • Your weapon getting dropped or bumped in storage or transit

Having a good zero and understanding how it works help to ensure quick, clean kills, so it’s among the hallmarks of an ethical hunter. Zeroing is easy, but it pays to get a head start so you’re ready for opening day.

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