map_setbombradius

The map_setbombradius is cheat console command. This command change c4 explosion range.

Usage

Enable sv_cheats 1
Use command once when map start: map_setbombradius 500

More details

This command either change already exist map entity info_map_parameters bombradius value or will create entity info_map_parameters if not exist.
C4 explosion radius is 500 by default, without info_map_parameters.
bombradius value is actually maximum explosion damage in dead center of explosion. To get explosion radius, multiply given damage with x 3.5

500 damage X 3.5 = 1750 radius