As said, Geo. Herter was quite proud and long winded about a cartridge (series) with multiple shoulders. Never saw one for sale, but don't pretend to be and expert on Herters business activities (just the lousy service). I Do miss the old blow hard. Amusing reading (and contradictions).
On the other hand, more reliable, there was research by a couple of "researchers" using the radius shoulder to create turbulence in the cartridge on the theory that it would at the same time, i). delay pressure rise by causing "swirling" during combustion and ii). encourage complete combustion thru the same effect(s). Names that come to mind PMVF, Powley, Miller, Venturified Freebore... This is well researched and thought of thinking in terms of internal combustion engines. CF the Chrylser (Mercedes) "hemi head". Then there is the "wedge head", don't recall the maker/promoter... I believe I read of it in Mr. Ackley's 2 volume books available from eabco.com, sinclair, ebay sometimes, etc...
Reportedly, this was behind the thinking of Mr. Weatherby and his double radius shoulder. And it has been suggested (after his death) that the 2nd radius was to make reamers harder to grind/copy (true, ask any machinist).
So, if you have the funds to fund such activity, you should experience some change. Enough to measure??? Improvement -???-???- Good question(s). Obviously not enough to be "commercially viable." luck
