Small arms in the ME universe are covered in the codex entries on "mass accelerator weapons," and the secondary on small arms. They are described simply as using electromagnetic force to propel slugs lightened in mass effect fields. They could be coilguns or railguns, but the latter are more consistent with mods in the game. That is "extended rail" mods in ME1, or "rail amps" in ME3.
My reasoning for calling the M-920 Cain a railgun was that railguns can achive speeds of 1000m/s, I divided this by 3.6 to get this number in km/h , whereas I should have multiplied it by 3.6 , calculated back into m/s that would be about 77m/s, a speed that I can link with the Cain. Mass Accelerator weapons being would also explain the constant need for thermal clips/venting, since the rails would otherwise get deformed because of the heat.
It does not matter that the Eagle is based off the Phalanx in lore speak. In any case it is a machinepistol since it is fully automatic. Read the description of the Shuriken or any of the SMG upgrades in ME2. There isn't much point in placing a machinepistol in the wrong category, except for contrived gameplay reasons, namely class specific bonuses (eg "Pistol Rail Amp").
ightened in mass effect fields.
When the Alliance's Offensive Handgun Project received funding to update one of its designs, its engineers chose to redesign the already impressivePhalanx pistol. Like its predecessor, the Eagle is a compact, fully automatic pistol that delivers unprecedented accuracy and punch with a rapid firing rate. The Eagle is named after the Desert Eagle, a classic handgun which gained a romantic reputation among gun collectors, thanks to its popularity in 20th- and 21st-century Earth action movies.
This would lead me to conclude they named it a pistol because:
1. It was a successor of the M-5 Phalanx, a pistol.
2. It is name the honor of the Desert Eagle, a pistol.
3. They tried to make a pistol, it simply wouldn't be nice as the project's overseer to say: ''Yeah, nice gun, but is not a pistol, it's a submachine gun.''
4. Apperently, the M-5 Phalanx is fully automatic, it's succosser is too, making them both Pistols.
5. They already had a N7 SMG.