CZ 805 Bren A2
The 805 Bren is CZ's answer to the need for a modular and reliable piston-operated selective-fire rifle. It is specifically built to switch between calibers and even magazine systems easily. Removing the barrel/piston system only involves 6 easily-accessible screws. Change the bolt-face and the rifle can shoot a range of different cartridges (5.56x45 and 7.62x39 are currently on contract and many more are possible).
Need to use M16/AR15 magazines? Pop two pins and swap the magwell. Add to that a true tool-less field strip and you have a rifle that can fit any role assigned to it.
Currently the Bren comes in A1 (14" barrel) and A2 (11" barrel) configurations with a monolithic 1913 top rail and accessory rails on sides and bottom. Its fixed folding stock can be quickly swapped for a folding, adjustable LOP stock or it can be removed altogether and replaced with a sling-swivel endcap. The Bren is selective fire, with settings for safe, single shot, two-round burst or full auto.
The 805 is piston-driven, with a user-adjustable gas system. To be lefty-friendly, the charging handle is reversible and the mag release is ambidextrous.
At current date, the Bren 805 is only available on military/law enforcement special order basis.