Hwasŏng rail
Hwasŏng rail (Menghean: 화성 도궤 / 華城導軌, Hwasŏng dogwe) is the informal designation, used in marketing and non-technical references, for a type of rail integration system developed and used in Menghe. Its formal designation is Type 111 weapon accessory mounting rail (111식 총기상 부대용품 표구 도궤 / 一一一式銃器上附帶用品表具導軌, il-il-il-sik Chonggisang Budaeyongpum Pyogu Dogwe). It is named for the Hwasŏng No.55 Arsenal, a major arms manufacturing center in Menghe, where it was first developed.
Design
The Hwasŏng rail consists of a metal strip with the cross-section of a wide hexagon on top of a rectangle, or a "T" with chamferred corners on the horizontal portion. Viewed from the side, it is lined with rectangular slots 5mm across and 2.2mm deep. Hwasŏng rails are milled from a single piece of metal, and are built to precise tolerance levels to prevent optics from shifting out of alignment during combat.
Depending on the application, the rail may be attached to a surface with screws or machined from the same block of metal as the upper receiver itself. On the JS-103 assault rifle and its relatives, the loosely fitted receiver cover can easily lose zero, and the rail is attached to a frame which wraps around the receiver and connects to a dovetail rail on the left side.
In contrast to the Picatinny rail, on the Hwasŏng rail the top surface is used for alignment and reference. This approach was found to offer better repeatability in tests carried out by other powers in Septentrion's Grand Alliance.
Uses
Like other rail integration systems, the Hwasŏng rail allows an operator to attach various accessories, such as telescopic sights, reflector sights, and night vision devices, to the rail, facing parallel to the rail's length and perpendicular to the rectangular slots. Accessories are first slid onto the front or back of the rail, then tightened in place by means of a lever, bolt, or thumbscrew.
While the Hwasŏng rail can theoretically be used to attach other modifications, such as foregrips and laser aiming modules, in Menghean Army service the rail is exclusively used for mounting various optics. Non-optic modifications are attached by means of Hwasŏng frames (see below). Menghean firearms generally include Hwasŏng rails on the upper receiver or upper foregrip, but not in any other locations.
Comparison with Picatinny rail
The Hwasŏng rail developed in Menghe and the Picatinny rail developed in the Organized States of Columbia are broadly similar in layout and role, but differ somewhat in their dimensions. For a unit of the same length, the Hwasŏng rail is slightly lighter, but also less sturdy, making it less optimal when mounting particularly heavy accessories. Other differences are described below:
- The recessed recoil slots on the Hwasŏng rail are 5.00mm wide, compared to 5.23mm on the Picatinny rail.
- The rail itself is slightly narrower at its edges, 20.2mm on the Hwasŏng rail vs. 21.2mm on the Picatinny rail.
- On both rail systems, the centers of the recoil slots are 10.00mm apart.
Without modification, optics designed for the Picatinny rail will not fit on a Hwasŏng rail, and vice versa. This had the added effect of forcing the Menghean Army to rely on its own domestically manufactured optics, rather than relying on foreign imports.
On the civilian export market, some companies manufacture stackable interfaces that connect to a Hwasŏng rail underneath and offer a Picatinny rail on top, allowing non-compatible optics to be matched. These are not manufactured by the Hwasŏng No.55 Arsenal, but rather by private arms companies in the OSC and Casaterra.
Hwasŏng frame
The Hwasŏng frame is a complement to the Hwasŏng rail. Introduced in 2016, it is based on the Columbian free-license M-LOK system and its slots are identical in dimensions. "Hwasŏng frame" technically refers to the style of handguard, which is custom-designed for each type of firearm but offers cross-compatibility with a variety of accessories.
In Menghean Army service, the two are not replacements but complements: the Hwasŏng rail, running along the top of the receiver, mounts optics, while the Hwasŏng frame handguard allows the mounting of other accessories that don't need to be directly in front of the shooter's eye, such as tactical lights, laser aiming devices, foregrips, and bipods. Compared to a handguard with rails of either type, the Hwasŏng frame is lighter and smoother, and can be made out of either metal or polymer.