I know I'm sorta necro-ing this thread, but I have some useful info to post.
And for the record, I do own a fire extinguisher 
so it would not have been the end of the world.
Like I said, lesson learned. Just accept it and move on lol.
The only fire extinguishers that will put out a lithium fire are D-class copper (NOT sodium) extinguishers. Any others will be just about useless. If you can't afford a Class D fire extinguisher, get a bag of playsand from Home Depot, and keep it in a dry area (inside. Don't store outside, as it will absorb moisture, which will make a lithium fire MUCH WORSE). It will be better than doing nothing.
Mine slightly bulged once but it went back down in about 10mins
Some bulging is normal for LiPo's when used near their C rating. Up to about 15% is a generally accepted. There's some newer ones out that only have about 5% bulging. 99% of Airsoft guns don't draw enough current to cause bulging, though, so that shouldn't be a major issue. Motor start, or a frozen motor (jammed gears) is what pulls the most current (typically 50+ amps on motor startup. Higher power rigs can pull even higher current than that).
~Brian
