That leaves me wondering why Winchester decided to make their current Model 70 safari express weigh in at 9.0 LBS for the 416 RM and 458 WM.
Because they dont produce magnum lenght action. So, smaller length action rifle will be of smaller weight.
Similarly you have ruger hawkeye african, in 375 ruger caliber, weight 8 pounds.
Some companies are aware of this issue, and like ruger they are fitting muzzle brakes on the barrels. But this is not overly appreciated by PHs.
Some not, zastava for example, m70 in 375 and 458 win mag, no muzzle brake.
The curse of medium action.
For average hunter, globally, short and medium length action will cover their their needs in variety of calibers from various centerfire 22's up to 300 win mag and 9.3x62.
This covers at least 98% of hunting rifle market. and 98% of demand.
DG calibers over 375, are rarely needed, except for African DG hunt, and Magnum length action thus becomes luxury, because no body produces it any more, except, very few elite workshops.
Common market factories with budget rifles, for DG hunters, are focusing on short magnums: like 375 ruger, 416 rem mag, 376 steyr, etc.
Because of smaller demand, magnum length action is not profitable to keep production going.
When factory winchester actually had the monopol on DG caliber market in late fifties and early 60ies, (with 375 and 458), I think they actually had profitable chance to start production of magnum lenght action, but they never did.
facing other technical and financial problems, they opted to phase out old pre 64 m70, and start production for new m70. so till now, we have current models in production. with pre 64 type model available again