SSA352 Universal Combat Rifle

The Sironan Small Arms 352 Universal Combat Rifle (SSA352 UCR; Sironan: Armeus Legereus Siron 352 Fuzil Gombat Universel, ALS352 FGU), is a 6.9x59mm SSA, gas-operated, magazine-fed rifle developed on Sirona in the early-2510s.
It was adopted by the Sironan Militia in late-2515 where it served to standardize the arsenal of the force, previously consisting of member-owned civillian firearms and surplus—often stripped-down—offerings from the UNSC. Remaining in-production from this date onward, it became the standard small arm of the militia throughout the rest of the , , and into the until the militia was finally dissolved by the in 2559 for failing to fall in line with the new government. The weapon—particularly its long-ranged variant—saw limited use within the UNSC forces during these periods, primarily by special operations units or locally stationed forces, with the latter especially taking up the rifle during the Siege of Sirona.
== History ==
== Design ==
The SSA352 UCR is a selective-fire, bullpup rifle with a conventional gas-piston-operated action that fires from a closed bolt. It was designed as a modular weapon system that could quickly be configured as either an infantry rifle or a DMR or sniper rifle with only a simple barrel change. Consideration was also made to introduce an open-bolt configuration to serve as a squad automatic weapon, but this never reached production as the SSA333 GPMG already in service was deemed fit to continue serving in this role. It is chambered in the high-pressure 6.9x59mm SSA cartridge and has the standard 1:255mm rifling twist designed to optimally stabilize all variants of the round. With the polymer casing of 6.9x59mm SSA, the UCR was expected to face decreased bolt and chamber wear and slightly increased barrel and throat wear compared to firearms designed for conventionally-cased cartridges, and as such it makes extensive use of advanced steel components for the internals. While the rest of the gun is composed of similarly advanced polymer and lighter-weight metallic components to compensate for the heavier internals, the rifle ultimately still comes in on the heavier side of available firearms, though by no means unmanageably or unusually so for its size.
The UCR consists of six modular assemblies: the barrel, receiver with integrated attachment rails, bolt carrier assembly, trigger group, polymer stock and body, and magazine.
=== Operating Mechanism ===
The UCR uses a rotating bolt to lock the chamber, featuring 8 lugs with a 22.5° boltlift to engage. This system is unlocked via a pin-and-camming-guide design, allowing the bolt to cycle. The bolt carrier itself is guided by a set of three guide rods running inside bearings in the receiver and containing the recoil springs. Depending on if the rifle is configured for left- or right-handed shooting, either the left- or rightmost locking lug also serves as the rifle's extractor, with a spring-loaded casing ejector. The rifle's ejection port can accept a casing deflector that redirects ejected casings downward, left as an optional attachment to avoid additional complexity and weight within the system and due to the lack of necessity for deflecting casings away from a shooter's face when using polymer-cased rounds. As such, off-handed firing of the weapon is possible comfortably with or without the deflector attached.
The UCR's gas cylinder is offset above the barrel and works with the topmost of the three guide rods. As part of the rifle's short-stroke piston system, this guide rod serves as the action rod, transmitting rearward motion from the gas-driven piston within the cylinder to the bolt carrier. Either of the remaining two guide rods can be set up with the forward assist depending on the rifle's handedness configuration, additionally allowing it to be utilized as a reamer and transmitting the force needed to remove any fouling in the gas cylinder. As another mechanism for getting around fouling, the UCR also features a 2-position gas valve, with the second setting using a larger borehole than the standard setting and allowing more gas into the cylinder during fouled conditions, aiming to provide a larger force down the cylinder and clear or operate past any debris.
The firing mechanism for the UCR uses a hammer-fired operation, contained within the rear of the stock and covered by the rifle's shoulder plate. Composed entirely of polymers except for the springs and pins—which are instead lightweight alloys to maintain strength while still cutting down on total mass—the hammer group lies in an open-topped box located between the magazine and shoulder plate, allowing the recoiling bolt group to travel over the top and reset the hammer during firing. With the trigger located well in front of the action, the actuation energy is transmitted through a linkage passing back alongside the magazine opposite the ejection port, allowing the spring's tension to release and operate the firing pin via the collision of the polymer hammer that had been held under pressure. Depending on the selected fire mode, this either actuates the rifle for semi-automatic or fully-automatic fire.
The UCR charging handle is non-reciprocating and is thus detached from the action during operation and remains stationary on the rifle, leaving no external moving parts.
=== Features ===
==== Muzzle Devices and Barrel Lengths ====
The UCR uses a hybrid, three-pronged muzzle device on the 460 mm (18.110 in) barrel, reducing flash with the prongs and providing muzzle braking and compensating action from additional ports in the device. The three prongs are slightly different in mass and geometry to reduce resonance-induced ringing without significantly impacting the harmonics of the barrel as a whole. The longer, 535 mm (21.063 in) barrel on the SSA352L variant uses a variant of the same muzzle device designed to provide a larger compensating effect as the flash is already less significant. This variant also has an integral folding bipod on the front end of the rifle, allowing better stabilization for the designated marksman than expected from the shorter-barreled version. Both muzzle devices are threaded to the barrel and are sized to fit a purpose-built external suppressor while remaining attached, allowing quicker exchanges between suppressed and non-suppressed operation of the rifle than a threaded suppressor would impose.
==== Trigger ====
The SSA352 and 352L both have a safe/semi/auto selective fire trigger group, with the selector located above the handle on both sides of the rifle, allowing easier ambidextrous operation. While originally intended to have a three-round burst rather than fully automatic fire mode, this was quickly eliminated in testing due to the inconsistent pull in burst-fire on an already sluggish trigger and for lessened efficacy in room-clearing situations compared to fully automatic fire. This comparatively sluggish trigger pull, however, remained in the production run of the rifle, though replacement trigger and sear lever groups were quickly offered by SSA for an additional charge, bringing the performance more in line with other rifles when installed.
==== Ammunition Feeding and Charging Handle ====
The UCR is typically fed from a translucent, double-stack, single-feed straight box magazine composed of an advanced polymer with a 25-round capacity and an empty weight of 200 grams (7.055 oz). However, it can also accept a 13-round, single-stack magazine of the same composition and a lighter 110 gram (3.880 oz) empty weight. The single-stack and double-stack magazines both have the same side-on cross-section, with only the thickness of the magazine changing between the variants, a feature compensated for in the magazine well by spring-locked magazine clamps which are able to lock both the thicker double-stack magazine and the thinner single-stack magazine. Both the SSA352 and the SSA352L accept and feed from the same magazines.
Due to the length of the officially produced magazines for the SSA352, several aftermarket single- and double-stack magazines of shorter lengths have been produced that the rifle can accept, providing fewer total rounds than their full-length counterparts while also not extending as far below the buttstock. These have seen fairly wide adoption by hunters and militia marksmen who are looking to reduce the necessary elevation of the rifle off the ground for shots fired while prone.
Loading the first round from either magazine is done with the low-profile charging handle to the front of the rifle, typically on the opposite side of the rifle from the ejection port. Pulling back on the handle moves the bolt back within the rear of the rifle, extracting a round from the inserted magazine to insert it into the chamber while also putting the hammer into its spring-loaded ("cocked") position. The handle can also be used to eject a round and cycle the weapon by pulling back on it with a round already seated in the chamber. As it opens the breech during this process, it can allow the operator to verify the chamber is clear of a round or obstruction, clear a variety of stoppages, and facilitate placing the bolt back into battery.
The SSA352 and 352L both feature a "last round bolt hold open" (LRBHO) feature, affording quicker reloads. When the final round of a magazine is fired, the UCR's breech is held open with the bolt locked to the rear position, allowing the magazine to be ejected, a new one inserted, and then the breech closed and ready to fire by the press of a button located on either side of the handle, just below the fire select. This button is constructed in such a way to allow operation from either side of the handle with either handedness. The bolt can also be released by pulling the charging handle back, though this is considered slower than simply pressing the provided button.
==== Sights ====
The UCR comes standard with a 1–8x32 "smart" telescopic sight attached on the upper rail of the rifle's body, a fire control system produced by Ognon Optik. Its unpowered state provides the operator with a "Christmas tree" style milliradian tick reticle, typically zeroed to 300 meters on the standard UCR and 450 meters on the SSA352L, though this can be chosen by the operator and further adjusted for windage and elevation with turrets that click to 0.05 milliradians and possess optional zero-stop capabilities. The reticle when unpowered can be illuminated ambiently, though the port which allows can also be blocked at the operator's choice to avoid distraction in situations where the illumination would be unwanted. The reticle is set on the first focal plane and the optic allows for parallax correction, ensuring that the reticle ticks remain usable without conversion or parallax at whatever magnification the fire control system is set at or what range the target is at. Furthermore, the magnification is configured in such a manner as to provide constant, generous eye relief at all magnifications—sitting at 9 centimeters—and a linearly scaled FOV to the magnification, ranging from 3 degrees at 8x, 6 degrees at 4x, and 21.81 degrees at "1x," not quite the expected 24 degrees due to the setting actually being a 1.1x magnification level.
When powered, however, the capabilities of the optics greatly increase. The most basic of these benefits is an electronically illuminated reticle and central aim point (with user-selectable color). However, the optic also contains a laser rangefinder capable of reaching out to 1 kilometer, local and remote atmospheric sensors, and an advanced ballistic computer to manage the received data in-situ. Pre-programmable for various rounds and able to switch between the ballistics data for each both at operator input and by reading the inserted cartridges, this system not only presents the user with the readout data (range to lased target, battery life, compass orientation of the aim, wind speed, and relative wind heading) but also takes that information (in addition to other factors such as non-wind atmospheric conditions and the motion of the target) and calculates a new placement for the illuminated central aim point, deflecting its position on the display. This allows the operator to avoid having to calculate the new aim point himself so long as the system is powered and operational, allowing quicker, more accurate fire on targets at range. Further sensors allow detection of and compensation for the presence of rotational reference frames—as would be commonly seen inside rotating 'artificial gravity' rings—deflecting the aimpoint to include the contributions from centrifugal and Coriolis forces. Beyond this, the fire control system also allows the operator to set waypoints on the display, allowing them to scan other areas while still being able to quickly return their rifle to the original target and reacquire the saved range data without using the rangefinder a second time, saving time if the target hasn't moved significantly. These waypoints can be easily wiped from the display to avoid distraction when they are no longer necessary.
Another means of reducing distraction in the optic is the presence of a 'CQB' mode that automatically activates in the "1x" magnification setting, temporarily clearing the display of everything except for the center circular illuminated aim point. The user can pre-select the size for this aim point and the tolerances around "1x" for which it remains the only function present on the display, ultimately allowing the operation of the scope as a pseudo-red dot optic (albeit not a true red dot without eye relief) and reducing distraction caused by the additional information.
The fire control system also has capabilities to connect to other members of the operator's unit—allowing shared waypoints—or to the operator's HUD using smart-link capabilities to avoid needing to sight on the optic itself. The smart-link functionality would project the entirety of the optic's displays on the HUD of the operator, providing a projected view down the sight of the rifle and all of the information that contains while still allowing a wider field of view on the peripheral and easier adjustment of the parameters from the externals of the optic. Altogether, the typical battery life of the system is 1,500 hours when relying on only the illuminated reticle, though more typical combat operation still saw around 350 hours of standard rangefinding and atmospheric sensing utilization.
While the fire control system is intended to be the primary sight for the UCR and has convenience features at low magnification, the lack of true 1x magnification, presence of eye relief (no matter how generous) even at the "1x" setting, and the slight green tinge when looking down the optic due to the glare-reducing coatings, the UCR comes standard with 45-degree canted backup iron sights for CQB situations. These sights are typically zeroed to 25 meters on both forms of the rifle and are positioned on the same side as the ejection port for the chosen handedness configuration. The backup iron sights were in the style of a notch at the rear of and a blade at the front of the body, with each side of the notch illuminated with a red tritium dot and the front blade illuminated with a green one for low-level lighting conditions.
The optic and backup iron sights—despite being designed for use in the rifle—are entirely removable and can be replaced by any optic and sights that work with the chosen rail system for the UCR in question.
== Modularity ==
=== Stock and Body ===
The UCR isn't fully ambidextrous in operation, with the ejection of rounds and location of the forward assist remaining only on one side of the rifle, but the stock and body is constructed for ease of swapping between left and right-handed configurations. All that is required to switch handedness is to change which side the blanking plate is on for the ejection port cutouts in the stock and to switch the forward assist to the preferred port and cap the other side.
Beyond this, there exists two forms of the stock and body component, one with the integral folding bipod and one without it, with the former typically found on the SSA352L and its civilian counterpart. However, this body is fully compatible with the receiver of the base SSA352 UCR as well, and the one lacking the bipod is compatible with the receivers for the larger variants.
=== Receiver and Charging Handle ===
The standard SSA352 UCR receiver has a restriction at the front to disallow heavier barrels and directly clamp to the lighter, shorter barrel of the base variant at the front, helping secure the weapon's internals from more rugged, close-quarters use and keep the thinner walls of the lighter barrel intact. However, this receiver is replaced on the SSA352L and its civilian counterpart for one that has a larger opening at the front that doesn't directly clamp to the barrel, allowing heavier, free-floated barrels to be affixed, only attaching in two places, the rear of the receiver via the chamber and the gas port via the guide rod of the bolt carrier (though this is a looser attachment). This variant also features slightly different spacing for the travel of the bolt carrier guide rod, as the thicker, heavier barrels displace the gas port upward relative to its location on the base variant. This further ensures that the correct receivers are used for the correct variants.
The civilian version of the receiver is further distinguished from the SSA352L receiver by the lack of a "fully automatic" setting on the fire select, instead offering only "safe" and "semi-automatic," pairing with the difference in internals between the two variants that prevent fully automatic operation of the civilian model.
=== Firing Mechanism ===
The UCR retains the same firing mechanism for the SSA352 and SSA352L variants, though the civilian variants are pinned to prevent fully automatic operation. Three-round burst firing mechanisms exist due to initial development in that direction, but remain rare as they are not offered to much of the civilian populace and were rejected in the early stages for adoption by the Sironan Militia.
Several aftermarket modifications to the trigger mechanism are available, ranging from simple replacements for the sear lever to complete drop-in replacements of the trigger group. While not standard, these saw widespread use among both civilian shooters of the SSA352 and members of the Sironan Militia to reduce both sluggishness and weight in the trigger pull.
=== Barrels ===
The SSA352 offers three types of barrels, two at 535 mm and with thicker walls and one at 460 mm with thinner walls. While the heavier, longer barrels are interchangeable and differ only in twist rate to account for different ammunition (the civilian variant at a faster 1:225mm twist to account for the lighter and slower lower-pressure civilian rounds), the 460 mm barrel shares the same twist rate as the military 535 mm barrel and instead differs due to thinner walls, shorter length, and different placement of the gas port relative to the centerline. This allows the two longer-length barrels to operate interchangeably with each other's respective receiver, but the 460 mm barrel only works with the base SSA352 UCR receiver and that receiver only takes that barrel in turn.
The civilian market does offer SSA352 CHR-compatible barrels in varying wall thickness and length from third parties; however, these are not endorsed by SSA.
== Variants ==
=== SSA352 UCR ===
=== SSA352L UCR ===
The Sironan Small Arms 352 Long Universal Combat Rifle (SSA352L UCR; Sironan: Armeus Legereus Siron 352 Len Fuzil Gombat Universel, ALS352L FKU) is a
=== SSA352 CHR ===
The Sironan Small Arms 352 Civillian Hunting Rifle (SSA352 CHR; Sironan: Armeus Legereus Siron 352 Fuzil Chaseu Sivil, ALS352L FCS) is a
== Gallery ==
== List of Apperances ==