Rebel Rifleman: Riflemen serving under the Rebel Army. They are frequently found hiding behind shoulder-high barriers (making them difficult to hit without using explosives) or in groups. When compared to Bazooka Rebels, they are somewhat more flexible in movement options (they can crouch and occasionally even run around unrestricted), but can only fire horizontally. They also have the option of using a melee attack, which swings much faster than other enemies', making them extremely dangerous up close.
Sometimes their animation shows them struggling to operate their rifle's bolt, then smacking their rifle against the ground a few times before being able to cycle it, hinting at their weapon being somewhat unreliable.
Wrath Rifleman: A Rebel rifleman ongoing a fit of rage. They're so enraged that they can fire and reload at rapid speeds. They cry out a victory yell once they're done attacking. Found in Metal Slug Attack.
Amadeus Corporal: Riflemen serving under the Amadeus Syndicate. Unlike other riflemen, they fire with AR-10 Autorifles stolen from the Regular Army. they can shoot diagonally, but the bullets move relatively slow. Beyond that, they have the normal range of attacks standard to soldiers. They are only found in Mission 6 of Metal Slug 4. In Metal Slug Attack, they wear purple uniforms to make themselves distinct from Regular Soldiers.
Amadeus Rifleman: Purple-clad riflemen serving under the Amadeus Syndicate. They use rifles that travel at a long distance. They are also able to rapid-fire multiple shots, but once they're done, their ammo shells become stuck inside the rifle's barrel. Found in Metal Slug Attack.
Researcher: Amadeus Syndicate scientists who defend themselves with rifles. Their ammo are syringes that transforms hapless victims into monkeys. A second hit as a Monkey is instant death. The Scientists' melee attack is a stab of a larger syringe with the same effect. They swing so fiercely that they can accidentally stab and turn themselves into monkeys if they miss their target. They are found in Mission 1 and Mission 6 of Metal Slug 4.
Elite Researcher: Purple-clad Amadeus Syndicate scientists who use piercing ammo. Found in Metal Slug Attack.
Ptolemaic Sniper: Snipers serving under the Ptolemaic Army. Their rifles have a higher rate of fire when compared to Rebels and have been modified with scopes. They are generally found hiding in bushes or beneath crates. They are only found in Mission 2 of Metal Slug 5.
Elite Sniper: Dark-clad Ptolemaic Snipers who are often hired to assassinate important figures. They are capable of stealth, inching slowly inside of their crates to get a better view on their enemy. Found in Metal Slug Attack.
- The rifles used by the Rebels could be based on the German Kar98, while the rifles used by the Ptolemaic Snipers might be based on the American M1903 Springfield or the Japanese Type 99 Arisaka.