I while back my roadster needed new brakes. I found that the pads on the backing plates were worn. I figured I would just level them off. How hard could that be? The car would not stop worth a darn. I bought new shoes and drums. I desided to see if the grinding job was accurate It was not. The wear on the shoes gave it away. The wear was slanted. I took a piece of scrap and drilled some holes in it so it would fit over a stud and a bolt could go thru on the other end. I swung it around and found the lowest pads and ground the high ones to match. I used a 1/4-20 bolt. A quarter turn moves the bolt is .0125". I found you can judge contact by the sound of the bolt dragging over the pad. I checked the shoes and they measured great. PS, I used my 4" grinder with a worn down wheel. .
That gets a "why the hell didn't it think of that 50 years ago when I was doing as many as 20 brake jobs a week." . That is the HAMB home made tool of the year.
A simple to make and easy to use tool. An elegant solution. Maybe a good time to also check end play and runout of the axle flange?
I took your advice. The flanges run dead on. No axial play in the axles My new drums are out of round. Bummer. Maybe turn them or buy others.
Obviously this may not apply, but if NEW can you take them back? I remember a rash of bad drums back in the 90s. Turns out, they had been stacked too high in the boat. The local store went through a pallet load by the time it was over. Times that by all the other stores. I don't know who the WD was, but that was a nightmare for them. After the manager came out to see a new out of box one he brought get chucked up in the lathe, our return policy was heavily relaxed for a while. BTW, all modern stuff for a long time has been 0.060" max cut. If they are under, you can try to cut them. If over that, they are fresh scrap.