The thickness of the recoil lug is part of chambering on actions without an integral lug… so if you change the lug, you change the distance to the shoulder of the chamber..
I.E. Don’t change the lug as others indicated (assuming it’s not an integral lug -then you can’t change it anyway)
Relieve the FRONT of the recoil lug recess… in the stock - it shouldn’t touch anyway.