I don't know how rare they are... but THIS is my non-kit CVA Mountain Rifle. It is a later "Made in Spain" gun sans the patchbox. In the Hawken vein, this .50 (my go-to BP rifle caliber) 33" blue barrel is 5" longer than my Thompson/Center's and has a LOP of 14". A highly stylized arm -- dark wood and contrasting Aluminum Pewter/German Silver furniture as well as Rocky Mountain front sight blade. The caplock and even wedges are case-hardened.
If yours is a Mountain Rifle too, the locks have a reputation for a soft mainspring that needs to be replaced eventually but otherwise, presuming they were careful in assembly, these are a quite decent rifle with very high accuracy -- the adjustable notch sight and double set triggers aid in that.