The Type-51 Carbine, also known as the Type-51, according to 343 Industries, was the Halo 4 version of the Covenant Carbine that first made its official appearance and head way in Halo 4.
The Type-51 Carbine is a Covenant recoil-operated and charger-fed, semi-automatic weapon. The Type-51 Carbine serves as the Covenant's medium to long-range weapon and fires an 8mm caseless radioactive projectile. The weapon's design is very basic, with unique differences. The first is its magazine placement, which is located right above the trigger guard - the weapon's cylindrical magazine holds 18 rounds, and also provides indication of number of rounds left in the magazine, using a holographic display. The back end of the weapon contains two circular openings, the forward one is the weapon's hand guard and the area in front of it is where the weapon's trigger is located. On the weapon's top rail is the magazine well and loader, below it is a hammer-like device which springs back when the weapon is fired. The forward part of the weapon contains the Type-51 Carbine's barrel which itself is well insulated to protect the shooter from the harmful radiation released from the round.
The weapon is also capable of 2X magnification, however it is not known where the magnification device is located. Kig-Yar Marksmen who are known to use this as an effective marksmen rifle and can be used to assassinate or pick off unsuspecting victims with the weapon's long-range capabilities. This weapon is the rival to the UNSC DMR. Sangheili Spec-Ops and regular Sangheili infantry are also known to carry it into battle as a medium range weapon, as well as Jiralhanae infantry.
The Type-51 Carbine marks itself as unique among Covenant firearms by its ammunition. Rather than using plasma bursts which can be inaccurate and slow at long range, this weapon utilizes caseless radioactive projectiles, shot out at supersonic speeds. It is unknown how or when the Covenant developed this weapon, but its ammunition is believed to be based on the Type-33 Light Anti-Armor Weapon's ammunition.
When fired, the projectile is powered along its entire flight path, consuming up to 50% of its total mass by the time it reaches its maximum effective range. Against light armored targets, the rounds' supersonic speed and super-heated nature ensures armor penetration on either the first or second impact. Impacts to the flesh can vary dependent upon range and speed - a single round impacting flesh at close range will penetrate deep into the target, and can nick bone.
The kinetic energy from the impact of a round at close range can knock back an individual. Two rounds that impact the same area at close range will pass through the target easily. At longer ranges the damage and kinetic impact is much weaker.
After a round comes to a halt inside the target's body, the round will continue to burn the victim's viscera until the round has cooled off. However, the aftermath of being struck with a round from the Carbine is moderate to severe due to the round's deadly radioactive nature. A surviving victim will require additional radiation treatments to ensure survivability.
The Type-51 Carbine, with its 2x zoom ability is an excellent ranged weapon. Its accuracy and performance in the field makes it an up front choice for infantry who are required to engage enemy infantry at medium range.
Its fast rate of fire is useful against more heavily armored infantry and is able to disable any type of infantry energy shield system including Jiralhanae Power Armor, Jackal Point Defense Gauntlets or Stationary Shield Generators.
The Type 51 Carbine also fits the role of a marksman weapon, as it can be used to take out a target from medium range, and the added bonus of low noise emission allows the carbine to perform multiple roles in the field. It also has a low recoil affect when fired and is shown to almost have no affect with active camouflage activated. This makes the carbine a perfect weapon for stealth operative missions.
The Type-51's rounds give off a light green trail, giving away the position of the shooter, a trait similar to shots from the Type-50 Sniper Rifle System's. The carbine's distinct sound at close to medium range may also attract the attention of nearby enemy infantry. Its firepower when compared to the human infantry counterpart, the Battle Rifle, is greater, yet slightly less accurate, though it still has the ability to take down almost any target. The Type-51, if fired too fast, becomes inaccurate, making it harder for the shooter to take down a target. Its magazine is also relativity small and may not be enough to take a target out; when faced with infantry with energy shielding it will require almost an entire clip to eliminate the enemy unless aimed at the target's head.