The MK18 upper receiver is the defining component of the USSOCOM CQBR platform. Whether you need a Mod 0 (10.3" Colt), Mod 1 (Daniel Defense 10.3"), or Mod 3 (11.5" Geissele URGI), every MK18 upper here is built to NSWC Crane specification — correct barrel profile, correct rail, correct BCG.
| Spec | Mod 0 | Mod 1 | Mod 3 (URGI) |
|---|---|---|---|
| Barrel | Colt 10.3" CQBR | DD 10.3" CQBR | Geissele/Colt 11.5" |
| Rail | KAC RIS II | Daniel Defense RIS II | Geissele URGI rail |
| BCG | Colt M16 profile | Colt or DD | Colt M16 profile |
| Muzzle | KAC NT4 mount | Surefire SOCOM | Surefire SOCOM |
All MK18 upper receivers shown below are in stock. Browse by variant using the sidebar — Mod 0, Mod 1, and Mod 3/URGI are all represented. Questions on compatibility with your lower? Contact CCC — we build these every week.