When you upgrade the indicated weapon you will be able to buy from the shop the corresponding firepower.
Unlock M93R (Samurai Edge custom):
Fully upgrade the M92F pistol.
Unlock Hydra Triple Barrel Shotgun:
Fully upgrade the Ithaca M37 shotgun.
Unlock Longbow (Sheva exclusive):
Fully upgrade S75 rifle.
Unlock Gatling Gun (Chris exclusive):
Fully upgrade the VZ61 machine gun.
Unlock Smith & Wesson M500 Magnum (HandCannon):
Fully upgrade the S&W M29 Magnum.
Added by: Sanzano Sep 25th 2009, ID#14335