I bought my son a new Tikka for Christmas. a TX3 lite Veil with the fluted barrel. We are using factory ammo. The ONLY one I can get to group is the Hornady 120 grain. That ammo shoots lights out, but anything else is well above MOA. Have tried Hornady ELDX 143 grain, Barnes 127 grain and Federal 130 grain. Wanting to shoot a heavier bullet but don't know what to do here. Anyone have any advice? If nothing grouped well I could understand maybe something wrong with the scope or mount or screws. Do these only like those lighter bullets or what?