The SteamClock is a bullpup pistol with a rotary breech system that is gas-operated in a blow-forward configuration. The Excalibur arms division was inspired by the H&K G11 rifle, differing on the caseless ammunition being substituted by the .38 Super Auto cartridge, needing for the aid of a blown-forward system to rotate the chamber, also mitigating some of its recoil as the barrel compresses the spring in the opposite direction, unlocking the chamber in the process and sealing it after each 90º spin. The decreased muzzle climb is also explained by its design, since the barrel is perfectly aligned with the shooter’s wrist when pointing the firearm.
With 13,40 cm (5,27 in) in height, 18,57 cm (7,31 in) in length and a barrel length of 8,59 cm (3,38 in), It is not much bigger than a Makarov pistol, but with most of its frame contained within the palm of the user it is significantly more concealable. It is wider however, with 3,3 cm (1,29 in) in favor of the double stacked 10 rounds magazine.
As the pistol uses an unconventional magazine, horizontally mounted on top of the barrel with its ammunition vertically facing down, much like the G11, with the cases also being ejected downwards. However, since the hand of the shooter involves the shooting mechanism, it ejects the spent cases between the user’s palm and little finger making use of a tube inside the grip, which can hold 3 cases if the ejecting port was not manually flipped, with the forth extraction forcing it open, discarding all 4 previous shells and remaining opened.
The pistol is virtually identical on both sides, enabling fully ambidextrous operation without the need of any modification as even the charging button, used to cycle the chamber, is present on either side and remains still while firing. Another feature is the threaded barrel shroud (in which the actual barrel slides inside), enabling the use of a specialized offset suppressor much like Osprey's.