Which grit sand to get to restore Constellation casebacks?

Recently someone asked about a caseback being original or not, it was identical to a restoration from STS - where they just sandblasted the entire thing away. After the members question, I decided to check whether there is any amateur sandblasting machines out there, and turns out airbrushes are ideal for the task, got one now

The restoration from STS is lazy, many possible ways to mask the stars and the observatory, they just blasted it away, but it doesn't look bad, worst comes to worse, it looks better than a polished caseback

My question is what grit dust I should get for the Constellation casebacks, higher grit would look better, but I think the original was much lower - there is up to 220 grit aluminium oxide dust available locally, and 0-800 grit "matte sand"

I was originally going to get the 400-600 mystery "matte sand", but leaning towards the 220 grit aluminium oxide as well, any experiences? Couldn't find any grit comparison photos online

I ended up ordering 180 and 220 grit aluminium oxide to test, probably going to go lower after the initial test

Quite surprising no one posted any photos of different sandblasting grits any easy to find place online

This is 180 grit with a weak blow, shiny part was masked

Not what I was imagining, but useful to reverse polished surfaces safely

I think anything noticeable would need a lower grit and a much stronger machine