I know this is an old thread but reading through there is some misinformation listed. The rarest caliber gun combination is the pre 64 model 70 .308 in STANDARD grade. I had an opportunity to purchase one back in the 80's new in box for $5,000.00. I believe it is worth around 10 times that amount today NIB. The .308 was only cataloged in the featherweight model 70.