Most of the weapons in Capcom's Resident Evil 4 remake can be purchased from the merchant, who adds more to his storefront as you progress in the game. The Red9 handgun is different: It's hidden somewhere deep, dark, and scary, but our guide will tell you where to find the Red9.
The Red9's location
You cannot obtain the Red9 until you reach chapter 4 of Resident Evil 4's remake. When this chapter begins, you find yourself in the Boat House with a sunken boat. What a terrible inconvenience. Fortunately, it's easily remedied. Follow the snaking trails into the Mural Cave. Nearby, you'll find a dock with a boat tied up next to it. (It's easy to spot on your map: Look for the boat icon.)
Jump aboard and steer your craft to a stationary boat in the middle of the lake. The boat was abandoned long ago, but her last captain must have gone down with the ship (figuratively speaking, since the ship is still on the surface), because there are treasures aboard for the taking. Dock your boat next to the marooned vessel and climb aboard. Your first stop should be the brown chest on your left; pop it open and pocket the Alexandrite stashed inside.
Head through the opening ahead of you and follow the path to your left. It'll take you up and around to the deck, where you'll find a larger, more ornate chest. Crack the lid and feast your eyes on the Red9!
The Red9 deals the most damage of any other handgun in Capcom's Resident Evil 4 remake, with the exception of magnum weapons like the Broken Butterfly, which are more like cannons than they are mere pistols. Armed with the Red9, your favorite shotgun, and a magnum, you'll be a force to be reckoned with in any boss fight.
If you played the original Resident Evil 4 on GameCube, PS2, or any in a long list of other platforms, you may notice that the Red9 is incomplete. There's a stock you can attach to gain extra precision while aiming and firing the weapon. You can find a guide for where to find the Red9 Stock as well as solutions to the Resident Evil 4 remake's many puzzles and requests in the Shacknews Resident Evil 4 strategy guide.