XM29 OICW Country USA Type Assault rifle Manufacturer Alliant Techsystems Introduction 2004 Specifications Weight 5.5 kg empty and 6.8 kg loaded (Objective) 8.2 kg loaded (actual) Length 890 mm Barrel length KE Module - 250 mm HE Module - 460 mm Caliber KE Module - 5.56x45mm NATO HE Module - 20 mm (Later: 25x40mm) Action Gas operated, rotating bolt Feed system KE Module - Various STANAG Magazines HE Module - 5 round box

The XM29 OICW (Objective Individual Combat Weapon) was the name for a series of prototypes of a new type of battle rifle that fired 20 mm HE airbursting projectiles. The prototypes were developed as part of the Objective Individual Combat Weapon program in the 1990s. The term SABR (Selectable Assault Battle Rifle) was also used at certain points, but is less common.

Developed by Alliant Techsystems, with Heckler & Koch as a major subcontractor, the most commonly seen version of the XM29 consisted of a semi-automatic 20 mm smart grenade launcher, an underslung assault carbine (derived from the HK G36 then in its late developmental stage) firing a standard 5.56x45mm NATO round, and a top-mounted computer-assisted sighting system with integrated laser rangefinder, thermal vision night vision capabilities, and up to 6x optical telescopic sight. Earlier designs used different configurations and setups.

The launcher part has been described variously as a light semi-automatic 20 mm cannon, a grenade launcher, or an airburst weapon. It poses a classification problem, in that it does not fit neatly into any one category. On one hand, it uses much smaller shells and has a much flatter trajectory than grenade launchers. On the other, while its calibre and velocity is more similar to light cannon, it does share traits with other infantry grenade launchers.

Various problems have effectively ended the program as it was originally envisioned, including weight, bulk, and lack of effectiveness of the 20 mm airburst round. Upon cancellation in 2004, it was split into three related programs.