I've noticed with one particular brand of practice ammo (ASYM 55 FMJ) a highly visible fireball every fifth or so shot out of the Bantam II on a 10.5" barrel. With this ammo I'd see this occasionally but much less often using a SF SOCOM RC2. This may happen with other types of ammo, of course, as well. If I switched to "serious" ammunition like MK 318 MOD 1 SOST, no flash was encountered. But, who among us buying our own ammo can afford to practice with the serious stuff more than a little?
With this practice ammo in a 16" gun with the Bantam II out front, no flash.
With this ammo in the 10.5" SBR with the Badger II 5.56 out front, no flash.
Based on my experience, I'd say the combination of this ammunition and the Bantam II on an SBR will lead to occasionally spectacular fireballs out front. Change ammo, go to a longer barrel, or switch to a bigger suppressor, and the problem is eliminated.
They call the Bantam II the "Bantam" for a reason. It's small - just 5" long and a little over 8 ounces. You can't expect miracles from it. My own Bantam II is a permanent fixture on my 16" rig:
I've now got a Badger II 5.56 in residence on my now ancient 10.5" SBR:
Putting my $$$ where my mouth is, there's now a TDS Nocturnal out front on my .300 BLK, as well:
I really like the TDS cans on my gas guns. They're unique - the lightest in the game, with good accuracy and repeatability, plus minimal back pressure and great signature reduction.