How to Box Test a Scope's Tracking at the Range

What a box test checks

Turrets are a promise. Each click claims to move the point of impact a fixed amount, usually 1/4 MOA or 0.1 mil. If you dial for distance or wind, you are trusting that promise. A box test checks two parts of it:

• Tracking: when you dial a set amount, does the impact move that amount, in the right direction, without drifting sideways?
• Return to zero: after dialing away and back, does the rifle shoot where it started?

The name comes from the shape. You dial up, then right, then down, then left, firing a group at each corner. On paper, the groups should make a square and the last one should land on the first.

A box test is a practical field check, not a lab measurement. It mixes the scope's behavior with the rifle's and the ammunition's, which is exactly why it is useful: it tells you how your whole system behaves. The site's review of the Sig Tango-MSR 3-18x50 mentions the method for that scope; this article is the general walk-through.

What you need

• A rifle that groups consistently with the ammunition you will use. If it does not group well, the test will be hard to read.
• Consistent ammunition, all from the same lot if possible. Match-grade or your usual precision load works best. Ammunition Depot's rifle ammo section has options by caliber, for example 6.5 Creedmoor and .308/7.62 NATO.
• A stable rest: bipod and rear bag, or a solid bench setup.
• A large target with a clear aiming point and a grid, or a plain sheet big enough for the whole box, with a measuring tape or ruler.
• A known distance. 100 yards or 100 meters makes the math simplest.
• A notebook or phone to log every move and every group.

The math you need

You only need two conversions, both from Wikipedia's milliradian article:

So if you dial 10 MOA at 100 yards, expect the group to move about 10.5 inches. If you dial 2 mil at 100 meters, expect about 20 cm. Pick a box size large enough to measure clearly but small enough to fit on your target.

Before you start, check your scope's manual for the click value printed on the turret. A scope with 1/4 MOA clicks needs 40 clicks for 10 MOA. A scope with 0.1 mil clicks needs 20 clicks for 2 mil.

Step by step

1. Check the mount. Before anything else, confirm the mount and ring screws are torqued to the maker's spec. A loose mount will ruin the test. The site's mounting torque guide explains why.
2. Set parallax and focus. Adjust parallax for the target distance and set the diopter so the reticle is crisp. The site's parallax explainer and diopter guide cover both.
3. Zero the rifle at your chosen distance. Note the turret positions, or set your zero stop if the scope has one.
4. Fire group 1 at the aiming point. Three to five shots. Mark it "1."
5. Dial up by your chosen amount, for example 10 MOA or 3 mil. Keep the reticle on the same aiming point and fire group 2. Mark it.
6. Dial right by the same amount. Same aiming point. Fire group 3.
7. Dial down by the same amount. Fire group 4.
8. Dial left by the same amount, which should bring you back to zero. Fire group 5.
9. Clear the rifle before walking downrange: magazine out, action open, chamber empty.
10. Measure center to center between the groups and compare with the expected movement.

Reading the target

A clean square, group 5 on group 1

The scope tracks and returns to zero, at least over the amount you tested. That is the result you want.

The square is too big or too small

If 10 MOA consistently moved the group more or less than about 10.5 inches at 100 yards, the turret may not be moving the amount it claims. Double-check your distance first; a rangefinder or measured distance helps. A small error in target distance changes the result. A taller-target style test, where you dial a large amount of elevation on a tall sheet and measure it carefully, is a more precise check for elevation specifically.

The square is a parallelogram or the vertical move drifts sideways

If dialing pure elevation also moved the group left or right, check that the reticle is level to the rifle and the rifle is level when you shoot. A canted reticle turns elevation moves into a diagonal. The site's mounting and zeroing guide covers leveling.

Group 5 does not land on group 1

The scope may not be returning to zero, or something else moved. Re-check mount and ring screws. If they are tight, repeat the test. Many shooters dial in the same direction when approaching a setting to reduce the effect of any slack in the mechanism; if that changes your result, note it.

Groups are too big to read

Then the rifle or ammunition is the limit, not the scope. Try a larger box so the movement is bigger than the group size, or improve your rest.

Before you blame the scope

A surprising result is a reason to re-test, not a verdict. Common causes that look like scope error:

• Loose mount, rings or rail.
• Inconsistent rest, position or cheek weld.
• Barrel heating and shifting impact over a long string.
• Mixed ammunition lots.
• Wind, especially at longer distances.
• Wrong distance to target.

If two careful repeats show the same error, contact the scope maker with your notes. Most will want the distance, the dialed amounts and the measured movement.

Scopes built for dialing

If you plan to dial regularly, look for exposed turrets with clear markings, a zero stop and matching reticle and turret units. Two examples from Ammunition Depot's listings:

The EOTech Vudu 5-25x50 FFP is listed with 0.25 MOA adjustments, an MOA reticle and EOTech's EZ Chek zero stop. Browse more in Ammunition Depot's rifle scopes or Optics Planet's riflescopes category.

Editorial note: This is an independent editorial overview built from manufacturer specifications, retailer listings and published sources. We have not performed hands-on testing of the products discussed, and nothing here is a performance guarantee. Verify specifications, compatibility and the law where you live.

Affiliate disclosure: Some links on this page are affiliate links to Ammunition Depot, Optics Planet. We may earn a commission if you buy through them, at no extra cost to you. Our editorial choices are not influenced by commissions. Check current price, stock and specifications directly with the retailer.