Some powders are more inclined to give a bright muzzle flash than others. There are some powders that are given a coating of flash deterrent, such as calcium carbonate. Ultimately, the best solution is to try several powders, and see which one gives the least flash in your particular pistol. Muzzle flash can frequently be reduced by trying different primers and a firm crimp. This will go a long way in reducing this problem.
Why do I have excessive muzzle flash in my pistol?
Sierra Bullets > FAQs > Why do I have excessive muzzle flash in my pistol?