One thing you should consider to make it "semi safer" (I am using that term loosely) is to get some cast iron pipe- ideally a foot long, and wide enough to fit the bottle into. That way, if it blows up, most the glass will be contained, other than the stuff flying way up... (none blowing out..)
Just a thought. Personally, I would not do this... I got better (safer) ways to play with gas/liquid/solid flammables...