Particle beam rifle
From Halopedia, the Halo wiki
The particle beam rifle is a type of sniper rifle system employed by the Covenant empire and its remnants. It fires an ionized particle beam at extremely high velocity, capable of dealing damage comparable to the UNSC's SRS99 series rifles. Beam rifles are commonly employed by Sangheili, Jiralhanae and especially Kig-Yar Snipers. At the outbreak of the Human-Covenant War, the Covenant did not effectively employ these tools, but lessons learned from observing human snipers placed a higher priority on the weapons seeing production and use.
The Covenant does not distinguish the various Particle Beam Rifle patterns from each other (at least, not to the obsessive level that the Office of Naval Intelligence tracks every refinement), and simply groups them together based on core components and intended use. Whatever their casing style and aesthetics, all are charged particle beam cannons of prodigious power – capable of killing shielded infantry in one or two shots, depending on accuracy.
The Type-27 beam rifle is an older model of rifle, and commonly favoured by Covenant remnant factions.
The Type-50 particle beam rifle is a newer model of beam rifle, seeing prominence towards the end of the war with humanity.