Your problem is designed into belted cartridges to ensure they will work. As I noted, the 300 Winchester Magnum has the same issue and there was even an extensive article in Handloader a while back saying all the same things that have been retold here.
The remedy for your issue is simple and has been well explained. Your issue did exist in 1912 (read up on how cordite powder cartridges were made)
The belt and set back shoulder (along with the body taper) reflected the genius of the cartridge's designers. The cartridge was designed to ALWAYS feed and chamber even in nasty humid places like India & Africa, into rifles that were just tools and treated as such. The combination of cordite powder, humid air, lots of dust and dirt, low tech cleaning methods and non-anal owners frequently lead to crud and rust in the chambers. With the set back shoulder and good old Magnum Mauser actions, you could be almost 100% sure that you could chamber a round and extract an old one before Mr Buff stomped on you. Nobody reloaded (generally illegal) so case stretch was a non issue.
Given the same conditions and ammo technology many of our modern wonder cartridges would result in "bad things". Sorta the same reasons a well used 1873/6 Winchester from out of own old West is almost never found with a perfect chamber and bore.
One of the reasons so many PHs are carrying 458 Winchesters today is the same. Simple, a big belt to headspace on, no issues keeping a straight sided chamber clean, big bullet moving slow, typically built on a Mauser or Mauser clone action that always seem to work when the chips are down.
