I think you won't be able to do this with bitsums, which means you would have to create a more dimensional variable, like:
PHP Code:
enum AmmoType
{
ClipAmmo,
BpAmmo
}
new g_Weapons[ 33 ][ CSW_P90 + 1 /*I think?*/ ][ AmmoType ]
Then you will have to set the variable for each player like
PHP Code:
new weapon = get_user_weapon( id )
g_Weapons[ id ][ weapon ][ BpAmmo ] = cs_get_user_bpammo( id, weapon )
g_Weapons[ id ][ weapon ][ ClipAmmo ] = /* you'll need to get the weapon's entity index to get clip ammo here */
You can save some memory and set for example bpammo to -1 if the user doesn't have the specific weapon.