300 Flanged? 300 H&H is a belted rimless cartridge. Flanged=rimmed cartridge? Never seen a 300 Flanged although I own a Martini-Hagn single shot in a 300 H&H as well as a Skodia sidelock O/U in the same cartridge. The 300 H&H is a very nice round based on the earlier 375 H&H, but it is also a belted, rimless rather than a flanged or rimmed cartridge.

But then again, I am not all-knowing so perhaps I am wrong or you are confusing the 375 Flanged with the 300, as the 375H&H belted rimless came out with the 375 Flanged as H&H's companion for DRs. Dave