[44 AMP]

I don't know where you got your info (or went to school), but while chemically listed as an oxidizer, O2 (oxygen gas) is extremely flammable, and explosive at the right concentration. The big NO SMOKING signs in hospitals (where oxygen is in use) are not there because of the risk of cancer from second hand smoke. They are there (and were there before smoking was known to hazardous) because of the real and immediate risk of FIRE!!!

Oxygen saturated clothing claimed more than one victim over the years before all the dangers were understood. There are slightly differeing definitions of "flammable" depending if you are in a chemistry lab, or working in an industry environment (and subject to DOT regs) but O2 meets all of them. As well as the regs covering a "compressed gas", for the bottles. Also, incidently, it is a corrosive as well, but this aspect is usually not apparent with short term exposure.

As was stated, gunpowder produces it's own O2 as it burns, so I would doubt that burning gunpowder in an O2 rich enviroment would have any significant effect on the burning rate. The powder isn't using O2 from the enviroment to burn, it is using the O2 in the chemical itself, so the amount of O2 in the enviroment doesn't matter to the chemical burn. Now, discharging a firearm in an environment with a high enough O2 content to ignite or detonate, that is a really, really bad idea. Slightly worse than checking your gas tank level with a lit match!