any way to tell if its a vanilla or modded weapon?

We would say modded.
There are only two crashes with this and both of them have mods
We are unable to reproduce it internally with vanilla game
In logs, there are some errors showing modded parts just before the crash.
Maybe it would be good to try it without these mods but again, there are only two crashes with this.

NightVision
Task Force Mattock Weapons
Task Force Mattock Uniforms
RIS Laser Attachments
Task Force Mattock BLUFOR OPFOR
BetterTracers
Zelik's Character
Suppressors

There are other crashes with that server but they are connected to memory and AI, navmesh specifically.