Thank you. I am not anywhere near your quality but I AM TRYING HARD TO GET THERE.Nice work. What are you using for a bore diameter?
For 7.62x39 it is recommended to stay anywhere from 8mm to 9mm. The smaller the exit the better the braking power of the muzzle brake. I stay with 8.5mm generally to avoid possible grazing of a projectile which would significantly diminish accuracy.