Kbk wz. 1988 Tantal

Design work began in 1984 at the state-owned Ośrodek Badawczo-Rozwojowy (OBR) in Radom, following a request from the Polish Ministry of Defence; the institute had studied a 5.45mm weapon since late 1980. Parameters were confirmed in 1985 and factory testing followed by the end of that year, with the first prototype batch built in 1986 for qualification trials. These early prototypes, designated wz. 1981, were based on the Soviet AKM. Because the weapon had to launch rifle grenades, it received a new multi-functional muzzle device and a reinforced folding stock, the wire stock being a copy of that used on the East German MPi-KMS-72. The wz. 81 also carried a mechanically limited burst mode taken from the AKMS wz. 1980 prototype developed at OBR in the late 1970s. The design was reworked by the end of 1987, introducing components interchangeable with the AK-74 — bolt carrier, bolt and magazines — and a refined burst mechanism. The improved prototypes were tested in January 1988, met requirements in 1989, and a pre-production batch was built the same year. Trials concluded in 1990, and in 1991 the rifle entered service with the Polish Army as the 5,45 mm karabinek wz. 1988. The design team worked under B. Szpaderski. Production was carried out by the Łucznik Arms Factory in Radom, exclusively with the folding wire stock.

The Tantal is a selective-fire, gas-piston operated weapon with a gas cylinder above the barrel and a rotating bolt locking to the right. A spring extractor sits in the bolt head and a fixed ejector in the receiver. The fire selector lever, on the left side of the receiver, offers automatic ("C"), semi-automatic ("P") and three-round burst ("S") fire, and can be operated with the safety engaged or disengaged. Burst fire is produced by a ratcheting device on the left side of the receiver acting on the trigger-disconnector and hammer pins; releasing the trigger mid-burst resets the ratchet, so the following burst is a full one. The manual safety lever is on the right side of the receiver in AKM fashion, blocking the trigger bar and limiting bolt carrier travel, with "Z" for safe and "O" for fire. Feed is from double-column curved box magazines of bakelite or stamped metal. The cold hammer forged barrel has a chrome-plated bore with four right-hand grooves and a multifunction muzzle brake usable as a rifle grenade launcher. The wire stock folds to the right and ends in a profiled shoulder pad; fixed wooden or synthetic AKM and AK-74 stocks can also be fitted. Handguards and pistol grip are bakelite, with a limited number of Tantal-specific black polymer parts produced; most wz. 1996 Beryl handguards are interchangeable. Iron sights consist of a forward post and a sliding tangent rear notch graduated from 1 to 10, plus a fixed "S" battle setting, with a radium-illuminated vial for low light. Issued equipment includes spare magazines, a 6H4 bayonet and scabbard, bipod, stripper clips with guide, cleaning kit, sling, magazine pouch and lubricant bottle. Ammunition — ball, tracer and training — was produced by Zakłady Metalowe "Mesko" in Skarżysko-Kamienna.

The Tantal formed the basis of the Onyks carbine, the karabinek-granatnik wz. 1974 rifle/grenade launcher, and a "night" variant with a receiver side-rail for the NSP-3 or Polish PCS-5 night sight. The Kbk wz. 1990 prototype rechambered the design in 5.56×45mm NATO but was rejected for lack of Polish Army interest. Poland procured 25,000 rifles, partially withdrawing them from service in 2005 with some retained in storage. Iraq bought 10,000 units from Poland in 2005–2006, and Poland donated rifles to Ukraine in 2022. The type has also been observed in Syria and with the Kurdistan Workers' Party.