I already know there is a few of you out there that are familiar with this scope,what I would like to know is what mm.would work best on12ga. or muzzle loader 42 0r 50mm and what the difference is in some of the 42's I went to a shooters supply and one of the 42's was $345.00 with a spotting scope and one was around $400.00 by it self both fullfield 42's is there a difference in the glass or what,I was also told I should get the ballistic plex for different yardage some experiance in this are would sure be helpful.