This is from the rulebook:
NON-INCLUSIVE list of EXCLUDED modifications:
-Externally visible modifications other than grips or sights
-Heavy barrels and/or barrel sleeves (factory or aftermarket)
-Add on weights of any type, weighted magazines
-Sights of non-standard notch and post type
Does anyone know if the Ashley 'half-moon' rear is allowed? Is that considered a 'notch and post'? Seems like it would be. Ghost rings are definitely out (although I don't know why... you can easily use them on a carry gun).