My understanding is for a few decades ammunition was hard to come by for traditional double cartridges, so manufacturers built more rifles in rimless chamberings typically associated with bolt guns. Since then, the ammunition availability has improved. These days doubles chambered in rimless cartridges are less desirable, and can be obtained for less money.
100% correct! My Heym 88B was made in 1986 in .458 Win. The .470 Nitro and other low pressure cartridges had been out of production since the British firm Kynoch ceased their production between 1960 and 1970. Federal re-introduced the .470 NE ammunition in 1989 and the .416 Rigby in 1991 with the Ruger Safari Magnum (RSM).
My .458 Win develops over 60,000 psi chamber pressure as compared to a typical .470 NE load of around 40,000 psi. The higher pressure of modern rimless cartridges creates higher “bolt thrust” where the cartridge head is rammed against the standing breach of the action and the barrels are simultaneously being pushed away. The higher pressure cartridges will certainly cause a break action rifle to loosen its action faster, perhaps much faster depending on the quality of the rifle and steel used, than the same make, model, and action size than a low pressure NE cartridge.
Modern doubles are offered in .375 H&H perhaps for convenience and familiarity of cartridge to many shooters. The .375 H&H with the same size/area of cartridge case head and less mass/energy being pushed through the barrels will resist action loosening more so than a .458 Win. That stated, without doing the math it is logical to think a high pressure .375 H&H will over many thousands of shots, cause an action to loosen much faster than a 450/400 NE.
What about a modern double chambered in .416 Rigby? The SAAMI PMAX or maximum operating chamber pressure for this round of 1912 vintage is slightly above 47,000 PSI. The PMAX of the .458 Win is 62,000 PSI. The pressure maximum of the .416 Rigby is 24% lower than the .458! Certainly, this in a god thing for a double rifle.
What about extraction of a rimless case? There’s the little problem. Spring loaded pawls or detents/fingers are pushed out into the extraction grove on a rimless case. When loading a rimmed cartridge double rifle in the heat of the moment, one only has to drop cartridges into the chambers. Rimmed cartridges must be pushed until the pawl snaps into place. In olden days’ ivory hunters with extraction only rifles could empty spent cartridge cases by turning the rifle upside down. This process made little sound compared to the metallic twang of ejectors shooting empty cases out of the rifle. Which could an angry elephant more easily locate the bearing of the threat?
Could ejection pawls fail? Of course as with any mechanical device. My old Heym as two pawls per extractor. I asked JJ Perodeau if the springs in my Heym’s pawls after 40 years should be replaced. JJ thought that was not necessary bases on his extensive experience.
If the cost is the same, for sure chose a double in a NE cartridge. While less powerful than a .416 Rigby, the 450/400 has an excellent reputation from John Taylor to present hunters. The 500/416 NE provides ballistics designed to match the original loading of the .416 Rigby of around 2325 fps for a 400 or 410 grain bullet. The choice is yours...
