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XM148 in the Remnants Museum in Ho Chi Minh City. By Lynndon Schooler.
XM148 in Vietnam. Photo credit unknown.
Episode 3121 of the Vietnam Veteran News Podcast will feature a story about the XM148 Grenade Launcher and its contributions to the American Military during the Vietnam War. The featured story is titled: The XM148 – America’s Early Under-Barrel Grenade Launchers in Vietnam. It comes from the Fire Arm Blog and was submitted by Lynndon Schooler.
Schooler reported that during the Vietnam War, U.S. troops faced intense close-quarters combat in dense jungles, exposing the limits of traditional small arms. While the M16 rifle was lightweight and modern, soldiers needed more integrated firepower. Enter the XM148 — America’s first serious attempt to combine a rifle with a grenade launcher.
Developed by Colt in the mid-1960s, the XM148 was designed to attach directly beneath the M16, allowing infantry to launch 40mm grenades without carrying a standalone weapon like the M79. Although about 28,000 units were produced, the XM148 was more of a stepping stone than a long-term solution.
The XM148 had promise: it was compact, fired the same rounds as the M79, and featured a basic sighting system. However, its design flaws quickly surfaced. The most dangerous was its exposed trigger linkage — an external bar that could catch on jungle foliage, risking accidental discharge of explosive rounds. Reloading was also clunky compared to the M79, and the mechanism to charge the weapon proved overly complicated.
Despite these issues, it saw combat use among Army units and Special Forces beginning in 1966. Feedback confirmed the concept was viable, but the XM148 itself wasn’t ideal. By 1967, the U.S. shifted to the more refined M203, which resolved many of the XM148’s shortcomings.
Ultimately, the XM148 played a crucial role in advancing infantry weapon design. Though flawed, it proved the feasibility of rifle-mounted grenade launchers and directly influenced future developments. It may not be well-known, but its contribution to modern small arms during a pivotal era earns it a lasting place in military history.
Listen to Episode 3121 and discover more about the XM148 Grenade Launcher and its contributions to the American Military during the Vietnam War.
