There are 2 types of attachments in Modern Warfare 2 Weapons Platform Specific Attachments and Universal Attachments. By levelling up weapons, you will unlock attachments that can be used across all weapons within the Platform, as well as attachments across all Platforms.
These are the Weapons Platform Specific Attachments, which are only usable within a specific Weapons Platform:
Weapons can use a mix of Weapons Platform Specific Attachments and Universal Attachments.
Check out the full list of Ammos in COD Modern Warfare 2 and Warzone 2 and click on the attachments to see how to unlock them, their stats, and the list of Blueprints that feature these weapon customizations.
All Ammunition Types in Modern Warfare 2 and Warzone 2:
@Guest That's why I'm here. the game persist I'm missing it but I have all guns it'd be linked too maxed leveled so I think it was scrapped by developers but someone forgot to remove it ooooorrrrrrrr it is upcoming and someone got a head of themselves writing it down