As I have handled several very old, original .416 Rigby rifles, besides more .350s and .275s, those guys did a pretty good job copying an really old Rigby .416 rifle. Those also came without cheekpiece or foreend tip (I have yet to see a genuine prewar Rigby with these features), with a closer pistol grip and a longer, fatter foreend than their No.4 .350s. They also had such a short rear sight rib, a barrel tapering to the front sling loop, the sling loop band set against a barrel step. Those old .416 Rigby No.5 rifles were not slim or elegant, but very substantial, if not to say clumsy. Just the "new" barrel is 2" shorter. Here is the page of Rigby's 1924 catalog that shows most of the features you complained about: