Every optic-equipped rifle needs backup iron sights — and Magpul's MBUS line owns this category. But should you buy the polymer MBUS 3 or the all-steel MBUS Pro? Here's the honest comparison. Browse both in Magpul MBUS Sights.
MBUS 3: light, refined, affordable
The third-generation polymer MBUS is the sweet spot for most builds. The MBUS 3 Front (£54.99) adds tool-less elevation adjustment and a dual-width front post; the MBUS 3 Rear (£69.99) gets a strengthened housing, dual apertures and crisp constant-tension deployment. At roughly 25 grams each, you'll forget they're on the rifle.
Choose MBUS 3 if: you run an optic as primary and want quality backups without weight or cost — a full set is under £125.
MBUS Pro: all-steel, run-as-primary tough
The MBUS Pro line is machined steel — sights tough enough to serve as your primary sighting system. The Pro Front (£95) and Pro Rear (£125) fold flat, lock up like a vault and hold zero through abuse. Want more? The Hooded Front adds post protection, and the Pro LR (£145) adds calibrated elevation for genuine distance work.
Choose MBUS Pro if: irons matter on your rifle — duty use, an irons-only build, or you simply want steel.
The offset option: speed with a magnified optic
Running an LPVO or magnified glass? The Pro Offset Front (£95) and Offset Rear (£125) mount at 45° — roll the rifle and you have instant close-range irons without touching your optic.
Head to head
- Weight: MBUS 3 wins — polymer is roughly half the weight.
- Durability: Pro wins — steel, full stop.
- Features: MBUS 3 has tool-less adjustments; Pro LR has calibrated elevation.
- Price: MBUS 3 set ~£125; Pro set ~£220.
- Both: fold flat, co-witness under optics, deploy instantly, hold zero.
Our verdict
For most optic-first builds, the MBUS 3 set is the smart buy. If your irons might ever be your only sights, spend up on the Pro. Browse all Iron Sights & Backup Sights — £5 tracked UK delivery.
Related guides: Best Upgrades Under £100 · M-LOK vs Picatinny
Choosing a mount to go with them? Our optic mount height guide explains 1.54in lower 1/3 versus 1.93in, and which heights let your MBUS sights co-witness.
