I am a contributing editor for NRA Technical Section Q&A. A reader has a custom Mauser 98-action rifle in caliber .350 APEX. He acquired it in 1969, and he says the cartridge is a 300 H&H Mag expanded to .35 caliber. It came with a set of RCBS dies marked .350 APEX, but RCBS says they have no record of that caliber. He wants to know who developed this and any other information on the cartridge.
I know about the Holland & Holland .240 Apex introduced in 1919. I’m pretty sure there is no connection. H&H registered the name APEX because they say it means “pointed bullet” in Latin.