Since 1959, the Czech Army relied on their venerable vz. 58 assault rifles, these weapons externally resembling the famous Soviet AK-47 but, internally, yielding an all-Czech approach. The system was chambered for the 7.62x39mm M43 cartridge and based its action on a gas-operated system utilizing a falling breechblock. Nearly 1 million of the type were ultimately produced into 1984 and several variants emerged from the family line. Czechoslovakia had peacefully split into the Czech Republic and Slovakia in 1993 and a concerted effort was then made to arm the new Czech Army with a modern assault rifle system to replace the aged vz. 58 line. Design on a new automatic rifle yielded the "CZ805 BREN" in 2009 and formal adoption into Czech Army service as the standard-issue service rifle occurred in 2010. The BREN name originates from the Czechoslovakian city of Brno in the Southeast Czech Republic.
Like other modern automatic rifles, the CZ805 is designed as a "modular" weapons system, essentially a weapon configurable to suit the mission role. This generally relies on the receiver and pistol grip/trigger unit remaining unchanged across the various guises - leaving the barrel, handguard, shoulder stock, optics and magazines to be altered as needed in creating a whole new weapon role such as carbine or light machine gun. As such, the base assault rifle can be configured to become a compact carbine form (retaining its assault rifle qualities), a "long gun" sharpshooter form or a light machine gun (LMG) for the squad automatic weapon (SAW) role. This certainly broadens the tactical reach of the CZ805 while, at the same time, becoming an economically sound alternative to the Army making multiple weapon purchases from various sources to fill inventories. The modularity of the CZ805 BREN is such that the base weapon can be changed in-the-field to become another weapon type firing an altogether different cartridge class. While generally chambered for the 5.56x45mm NATO cartridge, the CZ805 BREN can be adapted to make use of the 7.62x39mm Soviet cartridge with the intermediate 6.8x43mm Remington SPC possibly forthcoming. Most of the controls on the receiver are ambidextrous by design while the cocking handle can be switched to the opposite side of the receiver for left-handed shooters.
The CZ805 is a "select-fire" weapon system capable of semi-automatic (single shot), two-round burst and full-automatic fire as needed. This also plays well into the various roles the weapon can undertake in-the-field - from strict ammunition control to all-out fire support. The fire selector is within easy reach of the firing hand's thumb and doubled on either side of the receiver for ambidextrous operation. Outwardly, the CZ805 design exhibits a stout, robust appearance worthy of a modern automatic weapon. The overall design is rather conventional in its arrangement while the internal functions are rather ordinary. The stock folds over the right side of the weapon body but this does not impede weapon operation. The top of the receiver includes a long-running rail system for the fitting of accessories to include various optics including night sights. The lower forend and handguard sides are also prepped with rails for the fitting of flashlights, aimers and a vertical foregrip for a firm two-point hold. The magazine is translucent in its design, offering the operator a quick peek at his current ammunition count. These magazines are curved and detachable from the magazine well, fitted into the receiver just ahead of the trigger. There are iron sights at the rear of the receiver and at the front of the forend. Depending on the configuration, the barrel extends a certain distance ahead of the forend. As a gas-operated weapon, the CZ805 features a top-mounted gas cylinder with a bottom-mounted barrel assembly - consistent with other Kalashnikov-inspired designs since the 1950s. Overall weight is roughly 3.6 kilograms with an overall length of 910mm with a 360mm length barrel. Maximum range is out to 500 meters depending on optics, cartridge type, training and experience. The weapon feeds from a 20-, 30- or 100-round detachable box magazine with the 30-round count being standard-issue. The 100-count box is more common for the SAW role where high ammunition counts are a prerequisite. As with other Kalashnikov-type weapons, the CZ805 BREN continues support for the mounting of a bayonet.
The CZ805 can additionally mount a single-shot, breech-loading 40mm grenade launcher under the barrel to further increase the tactical "reach" of the standard infantryman. In its Designated Marksman Rifle (DMR) guise, the CZ805 is issued with a standard scope and bipod as well as an suitable, accurized barrel. The DMR can then be fielded alongside base infantry elements and provide repeat, accurized fire at ranges beyond that of the assault rifle unit. The SAW form can be similarly deployed, these units offering voluminous firepower "on call" as part of the squad. The carbine form is nothing more than a more compact version of the standard assault rifle breed and sports a folding shoulder stock with a shortened barrel and hand guard. All told, the changes drastically shorten the rifle's length, making it suitable for use by special forces, paratroopers and vehicle crews alike.
The CZ805 BREN has since been noted in two distinctly marked variants simply designated as "CZ805 BREN A1" and "CZ805 BREN A2". The A1 designator is believed to be the full assault rifle form with its 360mm barrel length. The A2 designated is believed to be the carbine version with its 277mm barrel length.