Heavier bullets - less powder = less flash?

[gemini1]

I assume due to case capacity, the bigger/heavier a bullet is, the lesser amount/weight of powder is used. If this is the case, would'nt this mean that there is less muzzle flash/fireball, say on a 16" barrel?

[fabguy]

In theory yes, in reality I haven't seen a difference

[Jonathan Doe]

LEO SWAT team snipers use "subsonic" 308 Win caliber ammo with 180 grain bullets with their suppressed rifles. It is very effective.

Their usual round is ammo loaded with 168 grain MK.

[gemini1]

Well not suppressed, say 16" 223/5.56 with muzzle comp and say 77grn bullets?