Instead of thinking... how about knowing.
Magnesium wool is what is inside many of the bulbs. My old flash-guns didn't have a capacitor, just 3volts of power from 2 c cells.
I don't know about enhancements as far as gas inside. Pure O2 would likely oxidize the wool and have a short shelf life.
That being said I did USE some bulbs a couple months back some of them DEFINITELY had more oooomph than others.
Some seemed about 4 stops under. The ones that fired like I remember in Christmas's of many years past exposed the film just fine.