Samsung Galaxy S4 (SCH-R970C) Firmware Overview
What is the latest SCH-R970C firmware?
R970CVRUFND1_RS, released April 28, 2014 with Android 4.4.2. The archive holds 3 official builds across 1 region (CSC). Each one is the full stock ROM (flash file) for Odin, not an OTA patch.
Is the Samsung Galaxy S4 still getting updates?
Most likely not: there has been no new firmware since April 2014, so Android 4.4.2 is the last version this model got. The final builds below are still the best choice for a clean reinstall.
All SCH-R970C firmware builds
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. Use HOME_CSC to keep your data, CSC for a full wipe.