I am a new to casting pellets/slugs and on my first try using an accurate 30-50 mold and my first casting my pellet/slug are measuring 7.53/7.58 mm. on the rear ring. Is this ok to shoot? Or are they to small to work right? Lead temp at 620/650 degrees. The mold never got over 175 degrees. My air rifle is a FX Dreamline Classic 30 cal. with factory settings. Any information would be greatly appreciated.