This rifle, along with two others in this auction lot 750 and lot 751, are factory prototypes that appear to be a sample of each of the calibers that the Model 70 Classic Sporter Super Express would later be offered in, those being, .375 H&H Mag., .416 Rem. Mag., and .458 Win. Mag., with this example in .375 H&H Mag. Manufactured without sights with factory drilled and tapped holes at the muzzle and forward of the breech, and standard barrel markings. The receiver top is drilled and tapped and left "in the white" with the experimental serial number "EXP173A" on the right side of the ring. Jewelled bolt body with pre-64 style extractor and knurled bolt handle knob. Checkered pistol grip stock with dual reinforcing bolts, raised cheekpiece, and solid rubber recoil pad. The included FN America Certificate of Provenance identifies the rifle by model and serial number, stating that is was previously a part of the Winchester Factory Collection where it was maintained by U.S. Repeating Arms.