The APC9 SD PRO SBR and the KH9S Covert from B&T are 9mm sub-machine guns offered in the civilian market as semi-auto only firearms. First off, we should break down the first gun's impressive string of acronyms to better understand its features: APC stands for Advanced Police Carbine (APC), since the series was designed to meet the needs of today's law enforcement and military units; “SD” stands for Schalldämpfer (German for "sound suppressor”), because this model has an integral sound suppressor that works with a ported barrel to reduce the noise signature and velocity of supersonic ammunition to subsonic levels under 130 dB.
“PRO” means that the firearms features performance and ergonomics improvements including dual auto-folding non-reciprocating charging handles, ambidextrous selector switch and safety, improved lower receiver ergonomics with side-positioned bolt hold open/release, replaceable M4-compatible pistol grip, and Magpul M-Lok accessory slots. Lastly, “SBR” describes this variant as a “short-barreled rifle” due to its rapid-deploy telescopic stock. Side folding stocks are also available. This model comes with a full-length suppressor and standard B&T 9mm lower, but in its APC9 lineup the manufacturer also offer variants with GLOCK lowers and compact or sub-compact suppressors (SD SubCompact). As for materials, the upper is aluminum, while lower is polymer. Barrel length of the APC9 SD PRO SBR is 5.7"/175 mm and the action is based on a hydraulic-assisted blowback system. Magazines with a capacity of 10, 15, 20, 25 or 30 rounds can be used. The B&T APC9 series is not cheap though: prices in the US start in the region of $3,500, depending on the model.
KH9S Covert, for personal defense or specialized military and LE use
The KH9S Covert is a bit more unusual variant of the KH9 family: here KH stands for “Karl's Hobby” – a reference to Karl Brügger, one of the founders of B&T – but the S in the name stands for "Sten". This is in fact a side-magazine-fed gun, which is reminiscent of the British Sten SMG of World War 2 fame. (A KH9B model also exists, featuring a helical-magazine inspired by the Russian PP-19 Bizon SMG...). Operating on a simple blowback system and chambered in 9x19mm Parabellum, the KH9S Covert has a top charging handle. Like all the KH9 Covert series guns – that are designed for portability and concealability in mind – the KH09S Covert also features a magazine well and pistol grip that fold 90 degrees. This way it can be stowed in narrow spaces with limited depth where a discrete approach is required, while still allowing for a rapid deployment. Unique to the KH9 Covert is its double-action trigger system. The selector switch offers three positions: up for safe, mid for fire, and downward to decock the hammer mass, enhancing operational safety. Barrel is 6”/152 mm long. KH9 Covert models in the US are priced at around $3,000.
