Magpul UCS Universal Carbine Stock (1913)

The Magpul UCS is Magpul's first universal 1913 stock and the most adjustable option in the category. The reversible hinge lets you swap between left-fold and right-fold without buying a different SKU, the half-slot height adjustment on the 1913 clamp lets you fine-tune the stock's vertical position on the host's rear rail, and two cheek risers (0.50 inch and 0.75 inch) ship in the box for shooters running LPVOs, prisms, or night vision mounts that push optic height above standard.

Length is adjustable from 7.6 inches to 10.6 inches across a 3-inch LOP range. Total weight is 18 ounces, which is heavy compared to the polymer FS1913 but in line with the A3 HDA3 and Black River ACX. The stock has a 5-degree downward drop to clear ejection ports when folded, height at the buttplate is 5.3 inches, and maximum width is 1.9 inches. Compatibility is universal: any host that presents a 1913 Picatinny rear interface, including the Sig MCX, Sig MPX, Stribog (with factory 1913 adapter), Scorpion (with HBI 1913 adapter), Kuna, B&T GHM9 and APC9, and an AR running the Law Tactical ARIC carrier with the ARIC 1913 Rail Adapter Plate.

This is a stock, not a brace, so it requires an SBR-configured host. Post-OBBBA the NFA tax on SBRs is zeroed and eForm SBR conversions are running days, so for most builds the UCS is now the right call over a brace if you want the cheek riser, LOP range, and reversible fold. For pistol-config builds stay with the FS1913, FS1913A, or HDA3 brace variants.