RigbyMauser
Congratulations on your choice. Mauser 66 are rifles of the utmost quality and of extreme accuracy, which slowly start becoming classic rifles, even if not yet as classic as their pre-WW2 Oberndorf siblings. I have been the happy owner of two of them since the mid-70's, one Europa model in 7x64 (proofed 1972) and one S model in 8x68S (proofed 1976)and never experienced any issue, both on the range and in the field. The only things I had replaced were the rose wood / white insert on fore end and pistol grip cap, as well as the white insert in the butt stock; I thought this looked 'too Californian'(such as Weatherby rifles in the mid-70's) for German rifles bearing the Mauser name and I had them replaced by more classical ebony work. You can determine your rifle's proofing year from its serial number and I can tell you how to do that if you wish.
Regards.
Louis