I talked with Brett yesterday and he said M4 not much different than others for cutting, drilling
and grinding before heat treat. Really tough on belts when hardened.
I will cut some on band saw when the garage thaws out.
Tim

"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
Albert Einstein

At Khe Sanh a sign read "For those who fight for it, life has a flavor the protected never knew".