This kit is available on the Marketplace.
https://www.artstation.com/marketplace/p/lp9q/hyper-realistic-unreal-engine-4-gunsights
Realistic gun sight Materials inspired by realistic shooters like Call of Duty Modern Warfare and Insurgency SandStorm. Includes 1x scopes as well as more magnified optics, Pretty much Drag and Drop. The system is fully modular so you can easily add the Materials to your own projects.
It is fully customizable and modular, Most of the 300+ hours spent on this went into optimization, the shader count for the base Depth scope material is only 100 Instructions and about 65 for the simple reflex Reticle Material. The shader count increases when the Glass lens is added but that is mitigated by the Use of LODs or similar techniques.