Was wondering if anybody knew whether or not the inserts in Williams,Anshutz,or Lyman type globe front sights are interchangable?I need a set of inserts. I found out that I have williams sights,But the williams cat. does not list insert sets . The only ones I can find are Lyman.It is on a Remington 540XR don't know if they are factory or not.Also does anybody have a reccomendation for size, dia.(I.D. and O.D.) of the rear aperture? It will be used for 50 yard target and some varmit within 75 to 100 max.Thanks for the help.............Swamp