This post is kind of inspired by another post, although this post has nothing to do with backpacks and defecating. That being said I think the premise of being able to disrupt other PMCs via messing with their stuff would be really cool.
An example that is quick to come into my mind, is the use of fake ammunition. Project Eldest son was basically an effort to plant faulty ammo in communist supply lines, Imagine being able to put a single bullet in one of your magazines that would blow up in your gun. The bullet would blow up in the gun when fired, causing it to be unusable for the rest of the raid. This would make it so enemies are less likely to pick up your gun. Not only that but it would fit in the game since your PMC is already making ammo in their hideout.
Another, more toxic thing to do, could be killing someone, than taking their gun and filling the barrel with cement or some other obstructive material. In Tarkov, a lawless place with closed borders, I personally would try and destroy any weapons I wouldn't be using. I would love to smash someone's meta M4 against a rock until the rail falls off and the barrel is bent in two. In fact, why not just pack their barrel with thermite or TNT? I think there are so many more ways BSG and Nikita could torture us! why not unlock their true potential.
Honestly, this post started out serious and then became satire, I do think that guns should be able to be destroyed though, they have durability for a reason and rn there is little reason to repair them.
