My Dad told me and we are both Machinist, if it is grooved a little, but the main dia. is within specs.
The new linings will break in to the drums.
Some shops that do brakes drums, would rather sell you new ones, than machine the old ones for less profit.
Anyway, that's what he taught me, good or bad.
He was born in 1927.

Don

1967 GMC 9500 Fire Ladder Truck
"The Flag Pole"
In the Stovebolt Gallery
1946 2-Ton grain truck
1946 3/4-ton pickup,
1953 1-ton pickup
1957 1-ton flatbed dually,
1954 Pontiac Straight Eight
Of all the things I've lost in my life, I miss my mind the most!