M203 12" Grenade Launcher from LMT - 37mm barrel, special purchase

The LMT M203 Grenade Launcher in the 37mm smooth-bore, 12" barrel configuration — built by Lewis Machine & Tool for M4, M16, and AR-15 host rifles, and a non-NFA item in this smooth-bore flare-launcher form.

• Genuine LMT manufacture — one of the select US contractors that has supplied M203 launchers to US forces
• Smooth-bore 37mm — non-NFA (flare launcher, not a destructive device)
• 12" barrel length matching the most commonly issued M203 variants on M16 rifles and M4 carbines
• Aluminum construction with matte black mil-spec anodized finish
• Mounts to standard 0.625" barrel profiles and GI-compatible barrel-nut handguards

Program and regulatory context

The M203 was introduced to the US military in 1969 as the under-barrel 40mm grenade launcher for the M16 family. It remains in service with US and allied militaries decades later, supplied by a small set of contractors — Colt and LMT among them. The 37mm variant sold here is mechanically and visually identical to the 40mm military pattern, but the bore is 37mm smooth and the launcher is classified as a flare/signaling device rather than a destructive device. That keeps it off the NFA register while still giving a clone builder the correct look and mount for an M4 SOPMOD under-barrel configuration.

The 37mm installs and operates the same way as the 40mm. It attaches to Government-profile barrel assemblies with the standard 0.625" front cut (the M4 barrel cutout) and a GI-compatible barrel-nut interface at the rear. Check the handguard manufacturer's compatibility notes before ordering.

Note: This launcher will NOT accept the 40mm rifled barrel. It is dedicated 37mm smooth-bore. Mounting hardware sold separately.

ITAR restriction: This item ships only to US Persons inside the USA and may not be exported without US State Department authorization.

We keep the LMT M203 on the shelf for the SOPMOD crowd and the historical Vietnam-through-GWOT clone builders. Order yours today.