In the Academy City Invasion arc, Accelerator takes an unidentified semiautomatic shotgun from a stolen Hound Dog van. It features a long barrel, a rail-mounted Aimpoint red dot sight, a magazine tube completely concealed within its handguard, and a telescoping wire stock similar to that of the Mk. 14 Mod 1 EBR. Accelerator replaces his cane with it to serve as a crutch for the rest of the arc. He is seen kiling several Hound Dogs with it, while conserving his now limited Esper powers to fight Amata Kihara with later on. Immediately before final confrontation with Kihara, he smashes the shotgun against the Hound Dog holding an unconcious Last Order, destroying it.
Assault Rifle
FN F2000
The Sisters all seem to possess FN F2000 assault rifles for defense and combat, during and even after the Level 6 Shift experiments.
SIG SG552
The SG 552 is seen used by Anti-Skill officers during the battle with the Golem Ellis in the Hyouka Kazekiri and Academy City Invasion arcs. Combined with its featured use in A Certain Scientific Railgun it can be presumed this is the primary firearm of Anti-Skill.
Tavor CTAR-21
In the Academy City Invasion arc, the Hound Dog mercenaries ordered to secure Last Order and hunt down Accelerator are armed with the IMI Tavor CTAR-21.
Sniper Rifle
Barrett M82A1
An unidentified Misaka clone uses a Barrett M82A1 to combat Accelerator at the start of the Sisters arc. It is nicknamed the "Metal Eater", for its full auto setting. Its rounds are deflected back at the Sister by Accelerator's Esper powers, destroying the weapon and injuring the Sister in the process.
Rocket Launchers
Panzerfaust 3
Amata Kihara is seen using a Panzerfaust 3 during the Academy City Invasion arc. He uses ut to shoot at the Hound Dog van Accelerator and Index are escaping in, only for the two to be saved when Vento of the Front teleports in the path of the rocket. Her magical barrier blocks and absorbs warhead's destructive properties.
Grenade
M67 hand grenade
Used by Anti-Skills during the fight with Sherry's Golem.