Does it need to be? No. But it will save you some time and some ammo. There is a few vids on Midway USA's site about scope mounting. Scroll down to Sighting-In a Scope on the left column.
http://www.midwayusa.com/General.mvc/Index/VideoLibrary
We've had a few discussions about it here, too:
http://longislandfirearms.com/forum/m-1287062047.62079/
http://longislandfirearms.com/forum/m-1277389965.41628/
http://www.midwayusa.com/General.mvc/Index/VideoLibrary
We've had a few discussions about it here, too:
http://longislandfirearms.com/forum/m-1287062047.62079/
http://longislandfirearms.com/forum/m-1277389965.41628/