Tomb Raider I-III Remastered Starring Lara Croft

This is quite a simple one if you are going for achievements on the side. But as a general tip I would highly recommend doing the Nevada section first as High Security Compound strips you of most of your weapons. (I believe this may have been changed in the remaster but its better to be safe than sorry). And remember if you already have a weapon it will be replaced with its respective ammo instead.

Personally I used this site https://georgtrek.tripod.com/~GeorgTrek/tr3/weapons.html to ensure I got all the weapons. As you can see there are many instances where a weapon will spawn and plenty in Antarctica. Using this I brought up an all pickups guide for the level I chose and worked my way through them this way.

If you would prefer not to do that. I will list one of each of the locations listed below:

Shotgun - Found in the first level Jungle. Hope up to your right and slide down onto a small platform (Ignoring the main slope) Once on this platform the shotgun is lying under inside a bush under a tree (There will a small gap to land on)

Harpoon Gun - Found in Coastal Village. After grabbing the Smugglers Key (Found underwater to the right as you spawn). Use it in a large hut ahead. Fall down the trap door, Walk to avoid a spike trap from the wall until you get to a large cavern with water at the bottom. Here there are 3 bunches of harpoon ammo and beneath the entrance is the Harpoon Gun.

Uzis - Found in Nevada. If doing all secrets you find this naturally. After climbing up and past the waterfall. you will come across a large cavern with a waterwheel. Instantly hook left and crawl under a rock in the corner to find a spot to climb. The Uzis are lying up here with a snake.

MP5 - (Leaving this explanation to Stella) https://tombraiders.net/
T. REX NEST (Cmdr. Bishop's Key): Move around the front of the downed aircraft. When you pass the thick, square tree trunk at the nose of the plane, instead of continuing all the way around to the other side of the aircraft, turn right, into the corner with the blocky, gray rocks. Here you'll find a passageway leading to a side area. Drop down, follow the tunnel, and climb out on a ledge with some MP5 clips .
NOTE: If you don't already have the MP5 SUBMACHINE GUN, you'll get it here instead of clips.

Desert Eagle - Found in Temple of Puna. If going for all secrets you will get this naturally. Kill the first Blowpipe guys and head up to room with large staircase that cuts back on itself. Once near the top of the stairs you can jump to the opposite wall and grab a ledge. (Doesn't visually look like one. But the ledge is between the regular wall and the skull wall close to the ceiling). Shimmy across to the left to found the secret along with 2 Desert Eagle clips and the Deagle itself.

Grenade Launcher - Found in Caves of Kaliya. Simply complete the level as normal and the Grenade Launcher can be found on the back platform of the boss fight on the floor.

Rocket Launcher - Found in Lud's Gate. If going for all secrets you will get naturally. After the trap room where the roof comes down to crush you. You will find yourself with a button on your right. Go forward, look left and jump and grab the ledge above. Climb the grates and get above the barbed wire. Now climb up. When imbetween the two circular looking vents. Jump backwards, Press right away to spin then grab the next grate quickly. The Rocket Launcher will be lying in here.

If you got all the weapons required the achievement will unlock when entering the final level after the Lost City of Tinnos. Called Meteorite Cavern

Happy Hunting.