The Stone Hatchet is a hidden weapon which unlocks after completion of the special quest. It was added to the game as part of the After Hours content update and became available on August 3, 2018.
If you’re looking for the Double-Action Revolver, here it is: Treasure Hunt in GTA Online.
To start the Bounty Hunting in GTA Online, you have to join an online session and play in Free Mode. In five minutes you’ll receive a text message from Maude. Read it, and in two minutes you’ll receive an email with a photo of the target.
When you read an email, an approximate location of the target will be displayed on the map. Unlike the note in the previous Treasure Hunt, the exact location of the target is random. You need to find the bail jumper by yourself. Try to hear the bell. The closer you are to the target, the louder it sounds.
According to information from @TezFunz2, each of the twenty areas contains twenty spawn points of the bounties. Screenshots with all these points on the map are below.
The target is on the street and not stand out among other NPCs. Turn off the radio and slowly drive inside of the marked area, it will be faster than go on foot. Look in that places where you usually can find pedestrians standing still. Don’t try to find the target in deserted places or in the areas of active gang attacks. It’s easier to do in the rain when there are few people on the streets. As soon as you hear the bell, go to the sound source until you notice the target — there will be a red arrow above it.
As in Maude’s missions in the singleplayer, the bail jumper can be killed or captured. In the first case, you’ll receive GTA$5000, and GTA$10,000 in the second case. To capture the target, you need to injure it with melee attacks or with a low-damage gun (shoot in the legs). After that, the criminal will follow you. Take it to Maude’s house and stop in the yellow corona. After a short cutscene, you will receive the money. If you kill the target, you don’t need to deliver the body anywhere, and you immediately get the money.
When you kill or capture the bail jumper, you receive a text message from Maude. After that, in three minutes you get an an email with a photo of the second target. There are five of them in total. You need to deal with the rest four in the same way.
When all the targets will be killed or captured, you’ll receive the last text message from Maude, and the icon of the chest will appear on the map — this is the final location of the quest. Go there and get the stone hatchet.
Stone Hatchet Challenge
When you acquire the weapon, you can perform the Stone Hatchet Challenge. Get 25 kills of other players or NPCs to receive a reward of GTA$250,000 and an exclusive access to this weapon in Red Dead Redemption 2 (you’ll have to login with your linked Social Club account).