S.T.A.L.K.E.R.: Shadow of Chornobyl

This weapon is Mole's possession. He is located in Agroporom Factory and he is a character essential to the main story - you'll be tasked with saving him.

There are three ways of getting this weapon:
1. Kill Mole after he showed you an entrance to Underground and loot his body.
2. Drop better handgun in front of him and he should pick it up, dropping Walker 9x18.
3. Wait for Spetsnaz to show up after he's done with you, let them kill him and loot the body.

While method 2 and 3 are unreliable at best, the best method is basically to kill him and loot him. Walker 9x18 is not a good weapon for a few reasons. Firstly you should have already moved from using handgun to more serious firearms. Secondly, it's only marginally better than Fort-15 you can get from a corrupt military outpost commander in Cordon.

I'd suggest killing him, getting an achievement, reloading and moving on.