A heavy tactical crossbow using full electromagnetic acceleration — essentially a miniature railgun formatted as a crossbow for ergonomic handling. The HCB-3 fires steel bolts at 300 m/s, sufficient to penetrate light vehicle armor and most personal protection systems. Unlike the Ouroboros XB-7, which supplements mechanical energy with electromagnetic assist, the Longbow is purely electromagnetic — there are no physical limbs, no string, and no mechanical energy storage. The 'crossbow' designation is a legal fiction that allows the weapon to be classified outside firearms regulations.

Arcturus exploits this classification loophole aggressively. The HCB-3 is, functionally, a coilgun that fires projectiles at rifle velocities with reduced acoustic signature. Its classification as a 'crossbow' means it is subject to archery regulations rather than firearms restrictions in jurisdictions that still maintain that distinction. The weapon requires no ammunition permit, no ballistic registration, and produces no cartridge casings for forensic analysis. It fires a featureless steel rod that carries no identifying marks.

The Longbow's acoustic signature is not zero — the electromagnetic acceleration produces a distinctive electrical snap that sound detection systems can register — but it is significantly quieter than conventional firearms and does not match any firearm acoustic profile in standard detection databases. By the time the system identifies the sound as a weapon discharge rather than an electrical fault, the bolt has already arrived.