With large frame(12&16ga) & small frame (20ga-410) extractors stacked on top of one another, modifying a 20ga extractor to fit/function in a 410 bolt would take 5minutes.
Sorry,I do NOT have any 28ga extractors to compare.
I grind a .020" flat...aka cold chisel tip into the extractor tip so it is not sharp...aka a wood chisel to prevent the tip from chipping/breaking.
Rem 12,16,20,410 870's,1100's,1187's w/ literally truck loads of ammo run thru each shooting trap/skeet/clays over the years w/o an extractor issue.