Rodman Laboratories XM235

Lore & Background

The XM235 was designed by a team at Rodman Laboratories, part of the Rock Island Arsenal campus, headed by Curtis D. Johnson. The team included Lonnie D. Antwiler, Larry C. McFarland, Arthur R. Meyer, Fred J. Skahill, Doyle L. White, Keith L. Witwer, and Richard L. Wulff. The weapon was merely a prototype, and Rodman Laboratories lacked the facilities or expertise to copy and mass-produce it. When the XM235 was selected for the 5.56mm SAW trials, Maremont Corporation and Ford Aerospace and Communication bid on the rights to produce an improved model rechambered in 5.56mm, designated the XM238.

The XM235 is gas-operated and belt-fed, with the belt carried in a 'b'-shaped drum magazine necessitated by the bullpup layout to avoid interfering with the grip. The receiver consists of two long round tubes positioned by a main hoop and front tube, with the barrel axis between them, giving symmetrical forces during firing. The belt feed is mounted on the upper receiver tube and driven by a curved groove barrel assembly with a cycloidal cam groove, resulting in a long, smooth feeding cycle with fewer parts than the M60 or MG3 feed mechanisms. The weapon has two interchangeable piston rods, a frame, and a bolt, with a hydraulic pneumatic buffer in the buttstock. The barrel can be replaced quickly via a spring-loaded folding cover on the jacket. The pistol grip/fire control group is offset to the right of the receiver, making it nearly impossible for left-handed soldiers to operate.

Reader's Guide

The XM235 was developed as part of the US squad automatic weapon trials, a program that sought a new light machine gun for infantry squads. It was chambered for the experimental 6×45mm SAW cartridge, which was considered essential for the SAW concept due to the inadequacy of the 5.56×45mm NATO tracer round beyond 800 meters. However, the difficulty of standardizing and supplying a third cartridge, along with the political challenges of forcing NATO approval, led to the dropping of the 6mm requirement. Subsequent testing in 1979–1980 used weapons chambered for 5.56mm NATO.

The XM235's design was innovative, with a bullpup layout, a symmetrical receiver for reduced recoil, and a feed mechanism with only one-third the parts of the M60 or MG3. Its maximum recoil was about 90 kg, much lower than other general-purpose machine guns. Despite being selected for further trials, Rodman Laboratories could not mass-produce the weapon, and the rights were bid on by Maremont and Ford Aerospace. The XM235 ultimately did not enter service, but its development influenced later designs and highlighted the challenges of introducing a new cartridge into NATO. The weapon remains a notable example of the experimental SAW contenders from the 1970s.

Did You Know?

• The XM235 was chambered for the experimental 6×45mm SAW cartridge, which was intermediate in size between 5.56×45mm NATO and 7.62×51mm NATO.
• The weapon's feed mechanism had only one-third the number of parts of the M60 or MG3 machine gun feed mechanisms.
• The pistol grip was offset to the right of the receiver, making the weapon nearly impossible for left-handed soldiers to operate.
• Rodman Laboratories was part of the Rock Island Arsenal campus and named after Lt.-Col. Thomas Jackson Rodman.