The Daniel Defense MK18 RIS II is a free-float quad Picatinny handguard for AR-15 and M4 rifles, built to the USSOCOM SOPMOD II pattern and bolting on through the six-bolt Bolt-Up System.
The MK18 rail as SOCOM specified it — Mil-Spec 1913 on all four faces, two-piece, and free-floating the barrel underneath.
Daniel Defense built the Rail Interface System to USSOCOM's requirements for the SOPMOD II programme, and the MK18 RIS II is the 9.55" version of it. Every face is Mil-Spec 1913 Picatinny, so lights, lasers, foregrips and pressure pads clamp directly wherever they are wanted with no adapters and no rail sections. The upper rail platform is uninterrupted, and the whole assembly free-floats the barrel for accuracy.
The two-piece design is the part that came from the programme: with the lower rail section removed, an M203 grenade launcher can be attached without additional parts and without special tools, because everything needed is integrated into the rail itself. Construction is aircraft-grade 6061-T6 aluminium with Grade 8 military-specification fasteners, finished in Mil-Spec Type III hard-coat anodising in FDE or Black.
This is a different generation and a different attachment system from the RIS III. RIS II is quad Picatinny; RIS III is M-LOK. Both use the same battle-tested six-bolt Bolt-Up System, and Daniel Defense made them cross-compatible, but the accessories you already own decide which one belongs on your rifle. On a UK straight-pull AR-15 the appeal of a quad rail is the same as it ever was: a hard mounting point exactly where you want one, on a tube that does not move.
Why shooters choose the MK18 RIS II
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Quad Mil-Spec 1913 rails — Picatinny on all four faces, no adapters needed
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Free-float barrel design — nothing loads the barrel through the handguard
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Two-piece USSOCOM design — the lower rail section removes so an M203 can be mounted without extra parts
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Six-bolt Bolt-Up System — the battle-tested attachment, with Grade 8 Mil-Spec fasteners
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6061-T6 aluminium, Type III hard-coat anodised — the finish Daniel Defense ships on its own rifles
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Uninterrupted upper rail — one continuous plane from receiver to muzzle end
What the MK18 RIS II fits
Fits AR-15/M4 upper receivers on the MK18 pattern, including UK straight-pull AR-15 builds, and mounts through the six-bolt Bolt-Up System onto its steel barrel nut. Rail length is 9.55" (243 mm) and Daniel Defense specifies a carbine-length gas system; inside diameter is 1.15" (29 mm), which is tighter than the RIS III, so check your gas block profile before ordering. Unlike the RIS III, this rail has no integrated sling swivel attachment point — add a rail-mounted one such as the Daniel Defense Rail Mount QD Swivel Attachment Point, which comes with its swivel. If you would rather have M-LOK than quad rail, the Daniel Defense RIS III M-LOK Handguard is the current generation.
Specifications
| Platform |
AR-15 / M4 |
| Fits |
Mil-Spec upper receivers, carbine-length gas; steel barrel nut for the Bolt-Up System |
| Type |
Free-float two-piece quad Picatinny handguard, SOCOM SOPMOD II pattern |
| Material |
6061-T6 aircraft-grade aluminium |
| Finish |
Mil-Spec Type III hard-coat anodised, Black or FDE |
| Weight |
14.1 oz (400 g) |
| Length |
Rail length 9.55" (243 mm) |
| Mount interface |
Mil-Spec 1913 Picatinny on all four faces; six-bolt Bolt-Up System |
| Brand |
Daniel Defense |
| MPN |
01-004-08020-011 · 01-004-08020-006 |
Quad rail, SOCOM pattern, free-floated. Order the Daniel Defense MK18 RIS II today — in stock at Xtreme Tactical Gun Parts with free tracked UK delivery in 7–10 days.
Explore more: AR-15 Parts & Accessories or browse all Daniel Defense.
