Samsung Galaxy Victory
The latest firmware for Samsung Galaxy Victory (SPH-L300) is L300VPBND4 with Android 4.1.2, released on April 24, 2014 for 1 region (CSC). Every official firmware build for SPH-L300, newest first: one row per build with all regions (CSC) that received it.
You can find the firmware on the model: SPH-L300 page.
Yes, all firmware files for SPH-L300 are 100% official, original, and obtained directly from Samsung servers.
To flash SPH-L300, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SPH-L300.