The Model 70 XTR had a detachable mag and can still be found around the $500 range in good condition. I've only shot one, a 7mm mag, but the accuracy and fit and finish was as good as my Black Shadows in 7mm mag and 300 Win mag. An XTR would make a great long range competition gun, hunter, or sniper weapon. I have also read somewhere that there were ten round mags for them available at one time, but I've never seen this personally.
If you have to have ten rounds I'd say buy an older Remmy 700 (not a POS built in the last ten years) and have a pro do the bedding, crown, and bolt lapping. There are ten round mags available for the 700 detachables. Also Savage makes an awesome out-of-the-box weapon called the 10FP/FPC/etc. in .308. There are a ton of options out there. But yes, the Winchester XTRs were/are pretty awesome weapons.
If you enjoyed reading about "Is there a magazine for Winchester Model 70" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!