Samsung Galaxy S4 (SCH-R970C) Firmware Overview
The archive lists 3 official builds for the Samsung Galaxy S4 across 1 region (CSC). The newest one is R970CVRUFND1_RS, released April 28, 2014 with Android 4.4.2.
How to Flash SCH-R970C Firmware
Put the Samsung Galaxy S4 into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Pick a build with the same or a higher Bit than the one installed — a lower bootloader binary will be rejected.