I have a little more suppressor experience and better understanding what I am seeing/hearing.
On that note, Witt’s flash hider front cap may work fairly well, at least on an 18" using Federal M193. I believe what I was chalking up simply as the flash hider not working was actually due to oxygen in the can burning off with follow up shots having little to no flash and comparable to using decent quality flash hiders. I didn’t realize first round pop is also a thing with centerfire cans.