Rather than simply using selectWeapon to select your default weapon after adding them to your player, it is recommended you use a script instead similar to the following, which caters for multiple muzzles:
SelectWeapon.sqf
// Desc: select default weapon & handle multiple muzzles
if (count weapons player > 0) then
{
private ['_type', '_muzzles'];
_type = ((weapons player) select 0);
// check for multiple muzzles (eg: GL)
_muzzles = getArray (configFile >> "cfgWeapons" >> _type >> "muzzles");
if (count _muzzles > 1) then
{
player selectWeapon (_muzzles select 0);
}
else
{
player selectWeapon _type;
};
};