Magpul MBUS 3 Sight Rear for AR-15/M4

The Magpul MBUS 3 Rear is a polymer dual-aperture flip-up backup iron sight for AR-15 and M4 rifles, clamping to any 1913 Picatinny top rail.

Dual apertures, constant-tension deployment and tool-less windage — the MBUS 3 Rear is the smartest polymer backup sight made.

The Magpul MBUS 3 Rear Sight (MAG1167) pairs the classic dual-aperture combat configuration — a large ring for speed, a small aperture for precision — with third-generation refinements throughout. The strengthened housing resists crush and impact, the slimmed profile stays out of the way of optics and hands, and the constant-tension spring snaps the sight up crisply from either side of the rifle.

Windage adjusts without tools via positive, tactile clicks, so zeroing a set of MBUS 3s takes minutes rather than a session. For optics-driven rifles that still deserve dependable irons — which is to say, all of them — the MBUS 3 remains the definitive value in backup sights.

Why shooters choose the MBUS 3 Rear

• Dual-aperture design — fast ring up close, fine aperture at distance
• Constant-tension deployment — positive and ambidextrous
• Tool-less windage clicks — zero with your fingertips
• Strengthened, slimmed GEN3 housing — tougher and lower-profile
• Three finishes — Black, Flat Dark Earth, Olive Drab Green

What the MBUS 3 Rear fits

Fits 1913 Picatinny top rails on AR-15/M4 pattern rifles, mounted at the rear of the receiver rail. You need clear rail behind your optic, so check the space your mount leaves. Pair it with the MBUS 3 Front (MAG1166) for a complete matched backup system, and zero the pair together.

Specifications

Complete your backup system. Order the MBUS 3 Rear today — in stock at Xtreme Tactical Gun Parts with £5 tracked UK delivery in 7–10 business days.

Explore more: Iron Sights & Backup Sights, AR-15 Parts or browse all Magpul.