Quick answer: The FAB Defense Ultimate AR-15 Upgrade Kit swaps the furniture you touch every time you shoot: a GL-CORE M stock with a hidden 10-round mag, a GRADUS reduced-angle grip, a PTK-M pointing grip with a VTS-M hand stop, RBS and FBS flip-up backup sights, and three ULTIMAG G2 30-round magazines. The five parts alone cost about the same as the whole kit, so the three mags come along nearly free. You need a mil-spec or commercial buffer tube, an M-LOK handguard and a flat-top Picatinny rail.
Stock AR furniture works. So do flip phones. If you've been eyeing a new stock, then a grip, then backup sights, one part at a time, this kit is the shortcut.
In This Guide
What's in the Box, Part by Part
1. GL-CORE M Stock (with a hidden 10-round mag)
Fits mil-spec and commercial buffer tubes, anti-rattle lock, concealed carrier with a 10-round ULTIMAG included.
The stock is where your cheek and shoulder meet the rifle, so it's the part you'll feel first. The GL-CORE M locks tight on the tube (no wobble), and the carrier hides a spare 10-round magazine inside the stock. Think of it as a reload you can't forget at home.
2. GRADUS Pistol Grip
FAB Defense GRADUS Reduced-Angle Grip
15° reduced grip angle for a more natural wrist position.
Factory AR grips are angled for a long, old-school stock position. If you run your stock shorter and square up to the target, a reduced angle keeps your wrist straight. That's what the GRADUS does.
3. PTK-M Pointing Grip + VTS-M Hand Stop
FAB Defense PTK-M Pointing Grip
Angled M-LOK grip for a repeatable support-hand position.
M-LOK hand stop that sits in front of your support hand.
The pointing grip gives your support hand the same spot every time. The hand stop keeps it from creeping forward toward the muzzle. Both mount straight to M-LOK slots. Not sure how M-LOK works? Read M-LOK vs Picatinny.
4. RBS Rear + FBS Front Flip-Up Sights
FAB Defense RBS Rear Backup Sight
Flip-up rear sight for the Picatinny top rail.
Batteries die and optics break. Backup iron sights (BUIS) stay folded out of the way until you need them, then flip up so you can keep shooting. More on that in our flip-up backup sights guide.
5. Three ULTIMAG G2 30-Round Magazines
Polymer 5.56 / .223 magazines. Three of them, on top of the 10-rounder in the stock. That's 100 rounds of capacity out of one box. Check your state's magazine laws before you order.
Will It Fit Your AR?
- Buffer tube: mil-spec or commercial. The GL-CORE M fits both.
- Handguard: M-LOK, for the PTK-M and VTS-M. A Picatinny-only handguard won't take them without adapters.
- Top rail: flat-top Picatinny, for the flip-up sights.
- Shipping: this kit ships to US addresses only.
The Price Math
Bought one by one from our store at the time of writing: GL-CORE M with its 10-round mag $107.95, GRADUS $23.95, PTK-M $41.95, VTS-M $19.95, RBS $52.35 and FBS $34.45. That's $280.60 for the five parts. The kit is $280.95 and adds three ULTIMAG G2 30-round mags. In other words, the mags cost you about 35 cents. The kit page shows the live math.
Installing It
Unload the rifle, lock the bolt back and check the chamber. Then:
- Stock: pull the adjustment lever and slide the GL-CORE M onto the buffer tube until it locks.
- Grip: remove the grip screw, swap in the GRADUS, and don't lose the safety selector spring and detent.
- Foregrip: mount the PTK-M and VTS-M in your M-LOK slots and tighten the T-nuts.
- Sights: clamp the RBS at the rear of the top rail and the FBS up front, then zero them.
The Good and the Bad
- Good: the parts you touch most, all from one maker, and the mags ride along nearly free.
- Good: no gunsmith needed.
- Bad: the foregrip parts need an M-LOK handguard.
- Bad: US addresses only.
FAQ
Does the FAB Defense AR-15 kit fit my rifle?
It fits AR-15 / M4 / M16 rifles with a mil-spec or commercial buffer tube. The foregrip parts need an M-LOK handguard and the sights need a flat-top Picatinny rail.
Is the 10-round magazine included?
Yes. It rides in the GL-CORE M stock, on top of the three ULTIMAG G2 30-round magazines.
Which colors does the kit come in?
Black and Tan.
Can I buy the parts separately?
Yes. Each part is sold on its own, but the five main parts alone cost about the same as the whole kit.
Do you ship it outside the US?
No. This kit ships to US addresses only.
The Bottom Line
If you were going to buy a stock, a grip and backup sights anyway, buy the kit and take the mags. See the FAB Defense Ultimate AR-15 Upgrade Kit →
