I own a Knight Super 45 DISC. The gun is supposed to be accurate to 200 yards and shoot 150 grains of powder. When shooting 150 grains the bullets tumble, i thought no big deal and decided to back it down to 100 grains. At 100 yards it will shoot 2 bullets in a nice group but it always will throw one. I cannot figure out what the problem is, i have tried different bullets, different brands of powder, even switched from pellets to loose powder. Please help!!