In revision
r549 and after, to have friendly fire kick in on the next to last level, gg_friendlyfire should be 2.
From
../cfg/gungame5/gg_default_addons.cfg:
//=========================================================
// FRIENDLY FIRE
//=========================================================
// Automatically turn on friendly fire when a player reaches "x" levels
// below the last level (+1)
//
// Example: gg_friendlyfire 1
// => The above will turn on friendly fire when a player reaches the
// last level.
//
// Example: gg_friendlyfire 2
// => The above will turn on friendly fire when a player reaches one
// level before the last.
//
// Options: 0 = Disabled
// <level> = Enabled
gg_friendlyfire 2