![Winchester Model 70 (.330) Post 64 Long Action Magnum Alloy Light Weight Ring Base Combination (xxx701 series) - store.TalleyScopeRings.com](http://store.talleyscoperings.com/cdn/shop/products/alloy_mounts1_3f820ff9-796f-4eff-8590-1a737181b636_1024x1024.jpg?v=1456300585)
0.330 inches, refers to rear hole spacing for drilled and taped holes on top of the receiver.
For .375 Winchester Magnum length actions
Winchester 70 Express Post 1964 (.330 Rear Mount Hole Spacing for .458 Win., .416 Rem, .375 H&H, .300 Weatherby, .300 H&H magnums, and 7mm STW)