Near zero and sight height
50 Yard Zero or 100 Yard Zero: Which Should You Use?
Quick answer
A 50 yard zero and a 100 yard zero cross your line of sight at two different points, and that choice changes close range holds far more than anything past 200 yards. For a slow, heavy .45-70 load, a rifle zeroed at 50 sits dead on at 50 yards while the same rifle zeroed at 100 is 2.07 inches high at that same mark.
Crimson Trace Brushline Pro 3-9x40 Shotgun Scope, BDC Slugger Reticle
$214.98 Full specificationsA shotgun slug scope, the kind of optic commonly zeroed at 50 yards because most slug shots happen well inside that range and the trajectory falls off steeply beyond it.
Best for: a dedicated slug gun in a shotgun-only season
Check price on Amazon
Vortex Diamondback 3-9x40 Riflescope, Dead-Hold BDC Reticle
$249.00 Full specificationsA general purpose hunting scope, most often zeroed at 100 yards because that is the distance nearly every range has a marked line for.
Best for: the buy-once hunting scope at a sensible price
Check price on AmazonA rifle's bullet leaves the muzzle below the line of sight by exactly the sight height, the vertical distance from the centre of the bore to the optical centre of the scope. It then climbs, crosses the line of sight once on the way up, keeps rising to an apex, and falls back through the line of sight a second time further out. A zero distance is simply the range at which you have told the rifle to be exactly on the line of sight, and everything else about the trajectory's shape is a consequence of that single choice plus the sight height.
A 50 yard zero and a 100 yard zero are not two versions of the same answer. They put that crossing in two genuinely different places, and the effect on your close range holds is larger than most shooters expect, especially on a heavier, slower bullet where the trajectory has more time to diverge before it settles down toward the chosen zero.
Why 50 and 100 yards are genuinely different zeros, not two versions of one answer
The working
G1 point mass model, BC 0.281, muzzle velocity 1,330 fps, sight height 1.5 in, load: 405 grain lead at a catalogue 1,330 feet per second
A .45-70 is used here because its slower, heavier bullet shows the effect of zero choice on close range holds far more clearly than a flat, fast cartridge does. The same underlying principle applies to any load, at a smaller scale.
Zeroing at 50 forces the trajectory to sit on the line of sight at 50 yards specifically. Zeroing at 100 forces that same crossing to happen at 100 yards instead. Between the muzzle and whichever distance you pick, the bullet's actual height above or below your line of sight is completely different depending on which zero you chose.
At 50 yards, a rifle zeroed at 50 is dead on while the same rifle zeroed at 100 is 2.07 inches high, a gap created entirely by the zero distance chosen, not by the load or the rifle.
Sourced figure
| Distance | Path, 50 yard zero | Path, 100 yard zero | Gap between the two |
|---|---|---|---|
| 10 yd | 0.78 in low | 0.37 in low | 0.41 in |
| 25 yd | 0.09 in low | 0.94 in high | 1.03 in |
| 50 yd | 0.0 in, at zero | 2.07 in high | 2.07 in |
| 75 yd | 1.32 in low | 1.79 in high | 3.11 in |
| 100 yd | 4.14 in low | 0.0 in, at zero | 4.14 in |
| 150 yd | 14.67 in low | 8.46 in low | 6.21 in |
Both columns are the identical rifle and load. The only variable is which distance the rifle was told to be exactly on the line of sight at. The gap column shows how far apart the two choices put the point of impact at each distance.
Does this matter as much on a flatter cartridge?
Less, but the direction of the effect is the same. Running the identical comparison on a 168 grain .308 Winchester at a catalogue 2,650 feet per second and a 1.8 inch sight height, the gap between a 50 and a 100 yard zero at 10 yards is only about 0.04 inches, invisible in practice. The .45-70's much lower velocity and heavier bullet gives the trajectory far more time between the muzzle and either zero distance to diverge, which is why the same zero choice produces a 2.07 inch gap at 50 yards on that load and a negligible one on the .308. Sight height and zero choice matter most exactly where a cartridge is slowest and heaviest, which includes muzzleloaders, slug guns and big bore lever action rounds.
What decides which zero is actually right for you
A 50 yard zero suits a rifle or a shotgun slug gun that is realistically never fired much past 100 yards, since it keeps the trajectory closest to the line of sight through the range where the shot will actually happen and avoids the higher mid-range rise a 100 yard zero produces on a slow load. A 100 yard zero suits anything meant to reach further, since it is the easier distance to confirm on nearly any range and it front-loads less of the trajectory's total climb into the first 50 yards.
Sight height changes this calculation directly. A taller mount forces the bullet to climb further before it can cross the line of sight at all, which pushes both the near crossing and the whole shape of the close range path outward. Two identical rifles with different ring heights, zeroed at the same distance, will not print the same at 25 yards.
Measuring your own sight height before trusting either column
- Confirm the rifle is unloaded. Open the action, check the chamber is empty, and leave it open for the rest of this. Nothing here is worth doing on a loaded firearm.
- Measure the barrel and the tube. Take the outside diameter of the barrel under the objective bell and the outside diameter of the scope tube, and halve each one.
- Measure the gap between them. Measure the vertical space between the top of the barrel and the bottom of the scope tube with a caliper or a feeler gauge.
- Add the three figures together. Half the barrel, plus the gap, plus half the tube, gives your actual sight height, usually somewhere from 1.2 to 3.0 inches depending on the rifle and the mount.
Sources
- Published factory load specifications: .45-70 Government 405 grain lead, and .308 Winchester 168 grain match
- G1 standard drag function, the published Ingalls and Siacci reference
Frequently asked questions
What is a near zero and why does it matter?
The near zero is the first point, closer than the chosen zero distance, where the bullet's rising path crosses the line of sight. Sight height and zero distance together decide where it falls. It matters because between the muzzle and the near zero the bullet is always below point of aim, and how far that extends changes exactly how much you need to hold at close range.
Is a 50 yard zero better than a 100 yard zero for close range shooting?
For a slow, heavy load like a .45-70, yes, a 50 yard zero keeps the trajectory closer to the line of sight through the range most shots at that class of rifle actually happen in. For a flat, fast load like a .308, the difference between the two zeros at close range is small enough that either works about equally well.
Why is my rifle 2 inches high at 50 yards when it's zeroed at 100?
Because a 100 yard zero on a slower or heavier load forces the trajectory to rise well above the line of sight in the middle distance before falling back to meet it exactly at 100. This is expected behaviour, not a scope or ammunition problem, and it is larger on heavy, slow bullets than on flat, fast ones.
Does sight height change where the near zero falls?
Yes, directly. A taller ring or mount forces the bullet to start further below the line of sight and climb further before crossing it, which pushes the near zero and the whole shape of the close range trajectory outward. Two rifles zeroed at the identical distance with different sight heights will not print the same at 25 yards.
Should a slug gun be zeroed at 50 or 100 yards?
Many slug guns are zeroed near 50 yards, since most shots with that class of optic happen well inside 100 yards and the trajectory falls off steeply beyond it. Check the specific slug load's published trajectory and your own typical shot distance rather than assuming one zero distance applies to every slug gun.
How much does the 50 versus 100 yard zero difference matter for a flat cartridge?
Much less than for a slow, heavy load. A 168 grain .308 at a catalogue 2,650 feet per second shows only about 0.04 inches of difference between the two zeros at 10 yards, essentially invisible in practice. The effect scales with how slow and heavy the bullet is, which is why it matters far more on a .45-70 or a muzzleloader.
Researched, not professional advice. This page is compiled from published manufacturer specifications, published optical and ballistic formulas, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are shooter convention rather than sourced numbers, and they are labelled that way wherever they appear. Ballistic figures come from a point mass model using the ballistic coefficient the maker publishes, so treat them as a starting point and confirm them on paper at a measured distance. Confirm your firearm is unloaded with the action open before you mount, level, torque or bore sight anything. Verify a zero only on a supervised range or a safe, legal backstop, know what lies beyond your target, and follow the law where you hunt and shoot, including rules on land access and permitted cartridges.