Particle Beam Rifle
From Halopedia, the Halo wiki
Summary
The Particle Beam Rifle or the Beam Rifle is the Covenant equivalent of a human Sniper Rifle. In this case, the Beam Rifle can have a scope of 10X and runs on energy, something like the Plasma Pistols and the Plasma Rifles, and also has 100 energy bars. This gives it an advantage over the human Sniper Rifle as there is not a need to reload, but it suffers from the overheating problems of other Covenant weapons, and once the rifle is used up, which occurs fairly quickly in around 25 shots, it is virtually useless. These rifles are abundant in Halo 2, being used primarily by Jackal snipers, and their scope is different from the human Sniper Rifle. This is only found in Halo 2.