Here is a handy video listing the locations for all 5 magazines, with text description as well.
Scav! Magazine Issue #1: Galactic Zone – Find the Star Control building and follow the rounded exterior walls to a locked gate on the left. The Scav! magazine is found near a ruined bus, sitting next to a loot crate on the wooden boxes.
Reward: Increases speech challenge success chance.
Scav! Magazine Issue #2: Junkyard – On the western edges of the map, find the junkyard and go upstairs through the interior stairs. Follow the path around to a computer desk (just past the hanging yellow ride seat) — the issue is right there on the desk next to a locked safe.
Reward: +25% Combat Knife and Switchblade damage.
Scav! Magazine Issue #3: Kiddie Kingdom – Travel up to the northeast corner to discover the Fun House. Fight through the Hall of Mirrors and jump across the rotating platforms to reach the neon green spinners. Enter the tunnel on the right and continue ahead straight through another neon tunnel to find the issue in a dead-end corner.
Reward: +10% Hand to hand weapon damage.
Scav! Magazine Issue #4: Grandchester Mystery Mansion – Move down to the southwestern corner of the map to find the spooky mansion haunted by ghouls. Go through the whole tour and stop at the Exit sign — enter the employee’s only door (pick the lock) and take the stairs up to an abandoned workshop. Near the entrance to this room, look on your right to spot the issue on some wooden boxes, near a red handcart.
Reward: +5% explosives damage.
You need to have the ability to pick a Master Lock for this issue
Scav! Magazine Issue #5: Dry Rock Gulch Theater – Enter the employee’s only area of Dry Rock Gulch and look for a pair of red cargo containers with wooden boards leading up to the garage roof. Cross from the garage roof onto the central building roof to discover the last magazine on a circular wood table.
Reward: +1 STR & +1 END if you have <= 10,000 caps / +2 STR & +2 END <= 1,000 Caps / +3 STR & +3 END <= 100 Caps.