FWD drum backing plate observation

[WE287GN]

I was going through my spare parts to see what I had for backing plates..
I noticed I have two with different finishes on them ..
In other words one is finished like as into be mated with a friction , and the other still has grooves in it..
I am going to take a leap here, and assume it has to do with the stackups between, the aluminum pistoned fwd drum set up and the steel pistoned fwd drum setup..Where we loose the 2nd wav steel in the steel pistoned setup?
I am also assuming we wouldnt want an unfinished backing plate against a friction like as in a steel pistoned fwd drum??
So if there is a steel in between the surface shouldnt matter right?

Thanks

 

[WE287GN]

Opps wrong button, couldnt delete

 

[WE287GN]

modding a fwd plate

Well I am going to assume the finish doesnt matter as long as there is some sort of a steel to mate with..
All that and I decided it would be best to cut from the beveled side anyway, to keep some meat on the thing