If they put the main outer slug at the same depth on all your balls, the inner insert can be either flush or under 1/16 to 1/8 of an inch, in most cases. You might have to file a little off the inner insert depending on the outer slug installation. good luck

Yes You can sand it all you want. It lockes at the bottom of th hole so you cant hurt anything. If you use the inner slug in different balls it must be a liitle lower than the outer slug. Thats why you want the outer slug in all your equipment very close to the same depth.