STK-54: Difference between revisions
m
→Design details
Stander0945 (talk | contribs) m (→Design details) |
Stander0945 (talk | contribs) m (→Design details) |
||
Line 78:
The STK-54 series of rifles are selective fire weapons operated by a gas-driven piston system similar to the one seen on the Volkian AR system. It uses ignited powder gases channeled through a vent in the barrel to drive a long stroke piston located above the barrel in a gas cylinder to provide power to the operating system. When fired, a portion of the propellant gases are evacuated into the gas cylinder through a 1.9 mm (0.08 in) port, drilled at a 30° angle in the barrel, and a channel in the gas block. The high-pressure gases drive the piston rod (which is attached to the bolt carrier) rearward. During this rearward movement, a cam slot machined into the bolt carrier engages a cam pin on the bolt and rotates the bolt, unlocking the action. The arrangement of parts on the bolt carrier assembly provides for a degree of free travel, allowing gas pressure in the barrel to drop to a safe level before unlocking. The weapon features a self-regulating gas system and a rotary bolt breech locking mechanism (equipped with two locking lugs), which is rotated by a helical camming groove machined into the bolt carrier that engages a control pin on the bolt. To the immediate rear of the chrome-plated piston head is a notched ring which provides a reduced bearing surface and alleviates excess gas build-up. As the bolt carrier travels back, it compresses the return spring guided in a hollowed section of the bolt carrier and the return energy contained in the spring drives the moving assembly back forward, stripping a new round from the box magazine and locking the action. The cocking handle is attached to the bolt carrier on the right side of the receiver and reciprocates with each shot; the handle is bent upwards allowing for operation with the left hand while the shooting hand remains on the pistol grip.
===
Early production model (Series A1. 1954-1955) were outfitted with barrels which had a rifling twist of four grooves, right-hand twist, one turn in 14 inches (1:355.6 mm or 64 calibers) bore - the same as one used on the semi automatic TK-38. After finding out that under unfavorable conditions, the reduced powder charge bullets the STK-54 was tuned to could yaw in flight at long ranges, the rifling was soon altered. Starting from series A2, STK-54s had an improved rifling with six grooves, right-hand twist, one turn in 12 inches (1:304.8 mm or 54.8 calibers) for increased accuracy and was optimized to adequately stabilize the K431 ball and K442 tracer bullets. Further improvements were made starting from Series A4 (1964-1969), as newer barrels were optimized for firing the heavier NK312 ball and long D410 tracer bullets and have six grooves, right-hand twist, one turn in 7 in (1:177.8 mm or 32 calibers).
All variants of the STK-54 are equipped with an drum aperture sight adjustable from 100m to 600m increments. The front post is fully adjustable for both windage and elevation zero and is enclosed in a protective hood. Low-light flip-up front blade and rear sight elements have three self-luminous tritium capsules (betalights) which are calibrated for 100 m when deployed. ▼
=== '''Feeding''' ===
The standard magazine capacity is 25 rounds. There are also 10, 20, 30, and 40-round box magazines, as well as 75-round drum magazines.
All magazines, including the 75-round drum magazines, were of heavy steel construction - this combined with "feed-lips" (the surfaces at the top of the magazine that control the angle at which the cartridge enters the chamber) machined from a single steel billet makes STK-54's magazines highly resistant to damage. This, however, made the standard magazines heavy but was not seen as a disadvantage due to their reliability.
Early STK-54 magazines had light sheet-metal bodies with prominent reinforcing ribs which weighed around 0.33 kg (0.73 lb) empty. A second generation steel-reinforced dark-gray 25-round 6.5x42mm magazine with a matte nonreflective surface finish was introduced starting from Series B1 (1974-1982), fabricated from steel-reinforced ABS plastic. Later production magazines were noticably black in color due to a change in surface finish. The second generation magazine weigh approximately 0.25 kg (0.55 lb) empty. This rapid transition from steel to mainly plastic magazines yields a significant weight reduction and allows a soldier to carry more ammunition for the same weight.
=== '''Sights''' ===
▲All variants of the STK-54 are equipped with an drum aperture sight adjustable from 100m to 600m increments. The front post is fully adjustable for both windage and elevation zero and is enclosed in a protective hood. Low-light flip-up front blade and rear sight elements have three self-luminous tritium capsules (betalights) which are calibrated for 100 m when deployed. [[File:Image054.jpg|thumb|286x286px|Standard-issued K55 No. 5 Bayonet, and ZK-55 Bipods.]]
=== Accessories ===
[[File:
A number of accessories were provided with the STK-54 in the Mirhaimian Realm Defence Forces as standard issued. These include a blank firing device, a standard model M55 No. 5 Bayonet, a web magazine carrier, as well as a foldable bipod which is attached to the bayonet sheath when in transport. All variants of the STK-54 has a foldable carrying handle built into the upper receiver of the rifle.
| |||