I'm running a bedell TI comp and have used or Tries just about every powder that is applicable for 38 sc and from my limited experience with open guns/comps I would say the chambers on the bedell comp are fairly large, but I've never noticed any flash while running the gun, but have been told by fellow shooters while using 3n37 that a massive fireball was flashing even then I didn't notice it from my perspective. I also see other open shooters with a heavy muzzle flash and they never seem to notice, or maybe they do but are adjusted to it. There's just so many combinations of powder, comps, bullets etc i believe it's about finding the right recipe for your particular set up which it sounds like you have done.
