Gatling Gun (Chris exclusive) - Fully upgrade the VZ61 then buy the Gatling gun from the shop
Hydra - Fully upgrade the Ithaca M37 then buy the Hydra from the shop
Longbow (Sheva exclusive) - Fully upgrade S75 then buy the longbow from the shop
M93R - Fully upgrade the M92F then buy the M93R from the shop
S&W M500 Magnum (HandCannon) - Fully upgrade the S&W M29 Magnum then buy the S&W M500 from the shop