A Colt M4A1 Block 1 SOPMOD carbine paired with a 37mm LMT launcher — a clone-correct tribute to the early-GWOT SOPMOD kit, legal for civilian ownership.
The M4A1 SOPMOD Block 1 is the small-arms configuration U.S. Special Operations Command adopted in the late 1990s to turn the standard M4 carbine into a mission-configurable weapon. Block 1 was not a rifle — it was a kit, a set of accessories issued around a Colt M4A1 carbine: the Knight's Armament M4 RAS quad rail, a vertical foregrip, a visible and IR laser, a weapon light, a reflex optic, and the M203 40mm grenade launcher. The program was fielded broadly across SOCOM through the early 2000s and remained the baseline small-arms kit until Block II began replacing it in the mid-2000s.
This carbine is built on the Colt M4A1 SOCOM 6920 base — the factory semi-auto civilian-legal version of the M4A1 — with a 14.5" SOCOM-profile barrel, chrome-lined and 1:7 twist, matching the program spec. The barrel is factory chambered in 5.56 NATO with the Colt A2 extended flash hider pinned and welded to a permanent 16" overall length. The handguard is the KAC M4 RAS quad rail, the same 4-rail Picatinny handguard Knight's built for the SOPMOD program.
The 37mm launcher is an LMT (Lewis Machine & Tool) unit with a 12" barrel, built to match the form factor of the M203 40mm. In 37mm configuration, the launcher fires signaling and less-lethal 37mm cartridges and is not a destructive device under the NFA, which is what makes it available for civilian ownership as a standard Title 1 accessory. The mounting geometry, handguard clearance, and leaf sight are set up to mirror the M203's installation on a Block 1 upper.
The trigger is the Colt factory military semi-auto group (4.5–5.0 lb pull). The stock is a standard adjustable M4 carbine stock. The vertical grip is the mil-spec M4A1 contract VFG (same OEM supplier as KAC). Optic is not included — this is a clone build, and the optic is the shooter's choice (Aimpoint Comp M2 or EOTech 552 are period-correct Block 1 selections).
The Block 1 period-correct muzzle device is the Colt A2 extended flash hider (as shipped). The Block 1 period-correct trigger is the Colt factory military semi-auto group (as shipped). If the builder chooses to substitute non-program-period components — these are not Block 1 canon, but are common modern upgrades — Charlie's offers them as optional paid services at build:
1) Muzzle device substitution to a Surefire SOCOM hider: pick a Surefire SOCOM muzzle device from the in-stock list, add the permanent muzzle device removal and pin-and-weld service, and we'll re-permanence to legal 16" OAL before shipping. Note: Surefire SOCOM is the Block II / post-Block-I hider — selecting it is a departure from Block 1 canon.
2) Trigger substitution: any Geissele or LaRue Tactical trigger added to cart ships installed at no charge — we keep the original Colt group. These are commercial upgrade triggers, not Block 1 issue fire controls.
We build these in small runs because the Colt 6920 base rifles, the KAC RAS, and the LMT launchers all move through our bench at different speeds. If you see this one in stock, it's the full Block 1 setup ready for your optic and light. Copy that — grab it while it's here.
