Geissele Super Modular Rails (SMR) are the standard for USASOC, FBI HRT, and Delta Force clone builds. Charlie's Custom Clones carries the full Geissele rail lineup — the Mk4 Federal Rail (FBI HRT correct), Mk13 M-LOK, Mk14, Mk15, Mk16 URGI rail — in all lengths and colors including Black, DDC, OD Green, and Iridium.
The Mk16 is the correct handguard for URGI and USASOC M4A1 builds from the 2018-2023 era. The Mk4 Federal Rail was issued to FBI HRT and other federal units. Browse current inventory below — DDC and ODG variants are noted in each listing.