Steyr Mannlicher has just been awarded a patent (US7698844) for an innovative rifle box magazine design. The patent application was first published by the USTPO back in 2008, so it may be already being used in some of the newer Steyr rifles (in the future I must start examining the magazines on new rifles).
The design allows for multiple cartridges to be fed from the same base magazine. A clip is inserted into the front of the mag which changes the feeding angle. This allows for cheaper manufacturing because one magazine can be produced instead of one type per cartridge offered.