It can be used for .300 Blackout and 7.62x39, but you will need to verify your own bullet drops and hold overs for the reticle. Here is the reticle information:
https://op2.0ps.us/pdf/opplanet-vortex-strike-eagle-1-6x24-and-1-8x24-ar-bdc3-reticle-manual-pdf.pdf
There is more documentation for this scope and reticle that can be found on the left hand side of the main product page.