A2 Battle Sight Zero: How to Set a 50/200 IBZ on Your Carry Handle AR

How to zero your carry handle AR with the A2 sight system — and why the 50/200 IBZ is the smarter choice for most shooters.

What Is an A2 Battle Sight Zero?

The A2 Battle Sight Zero (BSZ) is a factory-default zero setting for the M16A2/AR-15 A2 rear sight system. Out of the box, the A2 sight is configured for a 300-meter zero — the military standard. At that setting, your point of impact matches your point of aim at 300 meters with no holdover required.

But for most civilian and defensive use, the 50/200 Improved Battlesight Zero (IBZ) is a more practical choice. It gives you a nearly flat trajectory from 0–200 yards — the ranges that actually matter in a defensive or hunting context.

Why 50/200 Instead of 300?

The 300m zero made sense for military engagements in open terrain. For most of us, engagements happen inside 200 yards. The 50/200 IBZ keeps you on paper at both distances with a minimal hold, and the A2 sight system supports it natively — you just have to know how to set it up.

Fixed Carry Handle vs. Detachable — Know the Difference

Before you start turning drums, know what you’re working with. The A2 sight geometry differs slightly between fixed carry handle uppers (like a classic M16A2 or Colt SP1-style) and detachable carry handle uppers (A3/flat-top with a removable carry handle). The detachable handle sits slightly higher, which shifts your zero by a few clicks.

The table above shows click adjustments from the 300m base setting. Both setups reach the same zeros — you just use different click counts to get there.

How to Set Your A2 Sight for a 50/200 Zero

This process resets the drum’s baseline so your sight’s marked positions actually correspond to correct zero distances. You’ll need a 1/16″ Allen wrench.

1. Set the drum to 6/3 – Rotate the rear aperture drum until it reads “6/3.” This is your starting reference point.
2. Loosen the set screw – Use your 1/16″ Allen wrench to back out the small set screw on the drum. Don’t remove it — just loosen enough so the drum can spin freely from the indexing detents.
3. Turn the bottom drum up 4 clicks – While holding the top drum stationary, rotate the bottom drum upward 4 clicks. You’re physically repositioning the zero baseline.
4. Align the top drum to 8/3 – Rotate the top drum (the marked one) until it reads “8/3.” This re-syncs your reference marks to the new baseline position.
5. Tighten the set screw – Snug down the Allen screw to lock the drum in its new position. Don’t overtighten — just firm.
6. Come down 2 clicks (fixed handle) or 4 clicks (detachable) – From 8/3, click the drum down toward 6/3. Fixed carry handle: 2 clicks down. Detachable carry handle: 4 clicks down. Reference the chart above.
7. Zero at 50 yards using the front sight post – Head to the range. Fire a group at 50 yards and adjust your front sight post only — up to move impact down, down to move impact up. Do not touch the rear drum. When you’re centered at 50 yards, you’re also zeroed at 200.

Watch the Full Setup

This video walks through the exact drum manipulation process above. Worth watching before you hit the range the first time.

Bottom Line

• The A2 rear sight ships zeroed for 300m — useful for military, less so for everyone else
• You can reconfigure it for a 50/200 IBZ with a 1/16″ Allen wrench in under 5 minutes
• Fixed carry handle = 2 clicks down from baseline. Detachable = 4 clicks
• Always use the front sight post for final zero corrections — not the rear drum

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