If I may. The nomenclature for the March scopes is like this: The X in -X or -FX means that the thickness of the tube is 4mm, very strong. The -F means that it's First Focal Plane (or Dual Focal plane for the 1-10X24, and the 1.5-15X42.) If there is no F it's SFP, or fixed magnification
The glass to which you are referring is Super-ED glass and DEON calls that optical system, High Master or HM. If there is no HM, the glass is ED glass for all other riflescopes except those with a 24mm objective, which have traditional optical glass.
I know, it's confusing, but it gets worse. The riflescopes that have a Wide-Angle eyepiece are further labeled with a W, WA or Wide Angle.
So, the name of the 4.5-28X52 is actually March-FX 4.5-28X52 HM WA. (First focal plane, 34mm tube, Super-ED glass, Wide Angle Eyepiece.) They could have called it Fred to make it simpler.
The 5-40 to which you made allusion is the March-FX 5-40X56 (First focal plane, 34mm tube, ED glass, normal eyepiece). That could be called Sam. There is now a Gen 2 version of this excellent scope, with improved turrets and fast focus eyepiece.
The 5-42 is the March-FX 5-42X56 HM WA (First focal plane, 34mm tube, Super-ED glass, wide angle eyepiece). Could be called George. The Gen2 of this riflescope has the Shuriken or the Writable (PRS version) turrets and improved optical path for the extreme adjustment settings.
Then we get into the turrets. When they introduced the Shuriken-style turrets, they added X to the name to differentiate from normal, or tactical turrets. Then we now have the Writable turrets, that are an evolution from the Shuriken turrets.
I hope this clears up any confusion, and I will point out that I try to make sure I always refer to a riflescope with its full name.
