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How Much Elevation Do You Need for 1,000 Yards? Scope Travel and the 20 MOA Base

Come-ups at 1,000 and 1,200 yards for a 6.5 Creedmoor and a .308 in cold, standard and thin air, set against 60, 80 and 100 MOA of scope travel on a flat base and a 20 MOA base.

6 min readSolved with the Ballista engineUpdated October 2026

A common question on long-range forums goes: “Do I need a 20 MOA base to shoot 1,000 yards?” Answer it with arithmetic. A .308 with a 175 gr match bullet needs 41.0 MOA of come-up at 1,000 yd in standard sea-level air. A scope with 60 MOA of total travel, on a flat base, has about 25.8 MOA of up travel left after a 100 yd zero. It runs out 15 MOA short. A 20 MOA base fixes that. Whether you need one depends on two numbers: what your load needs at your longest distance, and how much up travel your scope really has once it’s zeroed.

What you need: the come-up at your longest distance

The come-up depends on the load and the air. Cold, dense air at sea level is the worst case. Thin air at elevation needs less.

On a 20°F day the .308 needs 2.3 MOA more at 1,000 yd than in standard air. At an 8,000 ft density altitude it needs 6.6 MOA less. So size the budget for the densest air you’ll shoot in, usually home in winter. The density altitude article covers why thin air needs less.

What you have: half the travel, minus the zero

A scope’s advertised travel is the total from one end of the turret to the other. Mounted on a flat base with the erector centered, the scope’s line of sight runs parallel to the bore. Only half the travel lies above that point.

Zeroing uses some of that half. At a 100 yd zero the bore points slightly up relative to the line of sight, to lift the bullet from below the scope to the crosshair: 3.87 MOA for the 6.5 and 4.25 MOA for the .308 here. You dial that up to zero, so it’s gone from your budget. That leaves:

up travel left = total travel ÷ 2 − zero angle + base cant

Scopes with MIL turrets usually state travel in mils. Convert with 1 mil = 3.438 MOA: 60, 80 and 100 MOA are 17.5, 23.3 and 29.1 mil.

A 20 MOA base tilts the scope nose-down relative to the bore by 20 MOA. That moves 20 MOA of travel from the down side to the up side. The chart puts the need and the supply on the same scale: elevation measured from the scope’s optical center, which is the come-up plus the zero angle.

Where each setup runs out

The pattern in the table:

• A 60 MOA scope on a flat base doesn’t reach 1,000 yd with either rifle in sea-level air. It stops the 6.5 at about 910 yd on a standard day. At 8,000 ft the 6.5 gets to about 980 yd.
• A 20 MOA base on a 60 MOA scope gives the same up travel as a 100 MOA scope on a flat base. Both put 50 MOA above center, and both carry the 6.5 to about 1,240 yd in cold air.
• The .308 needs more than the 6.5 everywhere, and the gap grows with range as its bullet slows: 6.4 MOA at 800 yd and 20.2 MOA at 1,200 in cold air. On a cold day even an 80 MOA scope on a 20 MOA base stops it at about 1,130 yd.

The other side of the budget: down travel

A canted base only works if the scope can still come down far enough to zero. With a 20 MOA base the line of sight starts 20 MOA low relative to the bore, and a 100 yd zero needs only about 3.9 MOA of it. You have to dial down about 16.1 MOA. A scope with less than about 32 MOA of total travel can’t do that, and one with only a little more has no down travel left for a short zero or a close hold-under. A 6 mil base is 20.6 MOA, so the same arithmetic applies to MIL scopes.

These numbers assume the erector is centered when the scope is mounted. Rings, bases and receivers all have small tolerances, so leave a few MOA of margin at each end, and check where your scope actually sits by counting clicks from the zero to the top stop. The scope tracking article shows how to check that the clicks you dial are the clicks you get.

When the turret runs out

Past the end of travel you can still hold over in the reticle. A MIL or MOA grid below the crosshair adds its full height to the budget. The reticle holds article covers holding. Dialing to the limit and holding the rest is a workable plan for an occasional long shot. For regular shooting at that distance, a base that keeps the come-up on the turret is simpler.

Sizing your setup

1. Find your come-up at the longest distance you plan to shoot, in the densest air you’ll see: cold, at your lowest elevation.
2. Add your zero angle. A solver gives it, or use sight height plus the 100 yd drop over 100 yd: about 4 MOA for both rifles here.
3. Compare the sum with half your scope’s total travel, minus a few MOA of margin.
4. If it doesn’t fit, a 20 MOA (or 6 mil) base adds 20 MOA. Check that the scope still has enough down travel to zero.
5. Verify at the range: dial your far come-up before the trip and see that the turret gets there.