LMT’s Confined Space Weapon: The Specialist’s Tool

By Oleg Volk

Maximizing Close-Range Effectiveness

The esoteric Lewis Machine and Tool Confined Space Weapon 300 (LMT CSW300) is the logical evolution of the many attempts to downsize the M16 rifle for special operations needs. Super compact variants like the Colt Commando date back to the late 1960s, but those had to be padded out to longer overall length with blast-reducing flash hiders to assist in cycling. The end result was a lightweight but marginally effective short barreled 5.56mm rifle used by some Special Forces and, as a survival carbine, by military pilots.

The main problem of the Commando was that its ammunition was optimized for much longer rifle barrels. From 10.5-inch tubes, it simply lacked the velocity to make a 55gr bullet sufficiently effective past 100 yards. 7.62x35mm also known as .300 Blackout was developed from the start as a cartridge for short barrels, with many loads optimized for sound suppressed use. Whereas 5.56mm tops out at 77 grains, .300 BLK provides 220 grain options at the same velocity. The cartridge works with all the same components, other than the barrel. Compared to the other traditional CQB choice, 9x19 in MP5 SD and similar submachine guns, .300 BLK gives both better subsonic performance and the option to run significantly faster supersonic bullets in the 110- to 150-grain range. Built from the ground up as a .300 BLK rifle, LMT CSW300 aimed to make the best of the recent ammunition and sound moderation developments.

LMT CSW300 Features

The core of the weapon is a 1:7 twist, 8.15-inch, chrome-lined barrel with a matched sound suppressor permanently attached for the total length of 11.8 inches. Thanks to that compact configuration, and the specialized reduced length 6-position stock and buffer, LMT CSW300 is only 24.3 inches long with the stock collapsed, 27.6 inches extended. Because it features both a sound suppressor and a barrel shorter than 16 inches even with the suppressor attached, it requires two $200 NFA tax stamps for individuals to own. The barrel and suppressor unit are removable for maintenance. The carbine is hefty for its size, with most...

This article first appeared in Small Arms Review V23N3 (March 2019)
and was posted online on February 1, 2019


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