First, you should probably ensure that the attachment you have is compatible with your gun.

you’re free to install an attachment either inside or outside of the inventory.

This is true even of unique named weapons you may find on your excursions throughout the Zone.

Concept art of a bar scene in Stalker 2, with a character behind the bar looking at the camera.

That brings this guide on upgrading Stalker 2 weapons to a close.

Cover image for YouTube video

The upgrade screen in Stalker 2, showcasing the various upgrades available on a specific part of a gun.

The player in Stalker 2 aims at an enemy using a holographic scope atop their Shotgun.

A close-up of the attachment selector UI element in Stalker 2, showing a cross-formation of buttons which you can use to select attachments on a gun.