My original post was referring to what I would regard as Jeffery's enduring legacy - his contribution to cartridge design, rather than as an innovative gunmaker. As such, the .600 bore was his sole preserve.

I would say that his 450/400 3" was a variant on what pre-existed, and the .404 Jeffery Magnum was perhaps Jeffery's answer to the earlier .425 WR Magnum; similarly for the .333 Rimless as a follow on from Westley's .318. As a result of your researchs his .500 Rimless seems to have been a minor deviation of the 12.7X70 Schuler, but it would be a stretch to call it a Jeffery development. He did not do anything in flanged .500 bore cartidges for doubles or singles.

Leaving aside the numbers of rifles sold in the various chamberings; in the context of the technology of the 1902/3 period, I reckon his .600 cartridge was his standout achievement.