You don't need a big budget to make a real difference to how your AR-15 fits, handles and shoots. Here are the upgrades we'd spend under £100 on — ranked by how much improvement you get per pound.
1. A better pistol grip (from £34.99)
The cheapest meaningful upgrade on the rifle. The Magpul MOE-K2+ (£34.99) adds a modern near-vertical angle with rubber overmould, while the BCM Gunfighter Mod 0 (£39.99) brings duty-grade ergonomics. Browse all Grips & Foregrips.
2. A quality stock (from £59.99)
Fit and cheek weld affect every shot. The Magpul MOE (£59.99) is the benchmark value pick; the Magpul CTR (£79.99) adds a friction lock for zero wobble; the B5 Systems Bravo (£89.99) is the mil-grade sleeper. See our stock guide for how to choose.
3. Backup iron sights (from £54.99)
If your optic dies, irons keep you shooting. The Magpul MBUS 3 Front (£54.99) and MBUS 3 Rear (£69.99) fold flat under your optic and deploy instantly. More in Iron Sights & Backup Sights.
4. A foregrip (from £39.99)
Anchor your support hand. The Magpul AFG-2 (£44.95) suits modern drive-the-gun technique; the RVG (£39.99) is the classic vertical. Running M-LOK? The BCM KAG mounts direct — no rail needed.
5. Proper sling mounting (from £34.99)
A sling is useless without solid attachment points. The Magpul M-LOK QD Sling Mount (£34.99) adds a flush QD socket to your handguard; the RSA QD (£44.99) does the same on Picatinny. Then pick a sling from Slings & Sling Mounts.
6. Shotgun owner? Transform the pump (£34.99)
The Magpul MOE M-LOK Forend for the Remington 870 — or the Mossberg 590 version — adds accessory mounting and a no-slip grip for £34.99.
Where the next £100 goes
Past this list, the biggest single improvement is a trigger — read our AR-15 Trigger Guide — or true ambidextrous controls like the Radian Raptor.
Everything above ships with free UK delivery. Browse all AR-15 Parts & Accessories.
Related guides: AR-15 Trigger Guide · Choosing an AR-15 Stock · AR-15 Grips Explained