It is also worth pointing out that getting a 375 H and H to feed is a different situation from a 416 Remington.
The tapered case and shallow shoulder angle of the 375 just wants to feed smoothly, as well as extract and eject readily.
The 416 case is much straighter,has a sharper shoulder and tends to be loaded with blunt nose bullets.
My Model 70 in 416 needed a little work to run perfectly. My Model 70 in 375 ran perfectly out of the box.
Probably no coincidence that Savage offered 375s but not 416s.
I'm sure the Savage can handle the pressure,and the 416 can be fit in the correct magazine box,
getting it to run properly for dangerous game will be challenging based on my experience with the level of feeding that I have seen in the Savage bolt actions that I have owned and used.
Yes, that's going to be very interesting to see what components I was able to gather up for the gun's cartridge feed, and then how the .416 Rem Mag wants to behave upon being directed toward the feed ramp and into the chamber
As you already know, both the .375 H&H Mag and the .416 Rem Mag have a belted cartridge with the same base diameter and overall length, and therefore only leaves the slight difference of how each casing tappers up to where the bottle neck starts.
Finding .375 HH magazines, springs, followers is difficult enough but the .416 components are like hen's teeth, and so I have been doing screen captures of all the 375 magazine parts that I can find.
Will even look into if the .375 HH follower can be machined to provide better alignment for the 416 cartridge.
I chose the Nosler .375H&H 300gr Accubond white tips for my Remington721 rifle, and the Barnes 400gr TSX for what will be the Savage .416 Rem Mag rifle
I seen LOTS of those blunt round-nose bullets on online shops, and I certainly know they will do the job on whatever they come intact with, but I like the aggressive looks of the bullets that come to more of a point and so that's what I went with ... as I had previously said, I'm not using either big bore rifle for big game but they're simply to enjoy having fun and making noise in the neighborhood.
The following pics are just for some visual comparisons/references: