Over the years of shooting I have noticed that muzzle flash will be reduced
when longer barrels are used.
My little J frame .38 snub nose lets me see what powders have a fast burn rate in a hurry
and what powders will put on a fire works show for me when I go to a indoor range or have to
shoot at sundown, as well as any "Smoke".

Some powders that have low flash are N320, Autocomp, Sihouette and BE-86 powder.
I will also toss in Sport and w231as a low flash powder if you carry it.

In the 9mm, if you like accuracy WAC is a great powder to test out if you can find it but I have only been able to find CFE-p or BE-86, the last times out.

I did find a section that showed factory ammo muzzle flash on Lucky Gunner
that had lots of great pictures, if you can find it.

Later.