Your rifle should be what's known as a Steyr-Mannlicher Model L rifle.
They were made from the mid-70's IIRC, until discontinuence in 1996.
It's their medium-length action, the short action being designated S/L, and the long action as M.
The Model L was available in three standard chamberings, .243/.308 & 5.6x57, with the .22-250 & 6mm Rem as a special order only.
The makers left the spirals on the barrel exteriors - from the hammers used to beat down a smooth-bored tube onto a reverse-rifled mandrel - as cool/different decorations, with a high-polish/blue.
The detachable mags are pricey, and somewhat hard to find, IMO.
The scope is exactly what it is, and the Apel mount is a common European model.
IMHO, you have a package there worth in the neighborhood of $2K, if not more - presuming mint condition.
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