Is 0.3 grams too hot for a gas airsoft gun that has 600 fps?

I have recently bought the Mk1 Tactical Sniper and im using 0.3 gram BBs for it. The BBs are very high quality but the gun doest shoot straight. When ever i fire it the bullet will zoom off into the left, right or above. It will very occasionally shoot straight but with little accuracy. It is also a gas gun, please help me and thank you for your time :)