The trigger on the beergun is connected to CO2. You purge the air out of the bottle with the CO2 before you fill the bottle. It ends up being just like normal beer in a bottle. No contamination. I use mine quit a bit and no problems. Its just a lot faster i think.
Why yes, yes I am a metrosexual!
On taps 1,2&3: Una Mas Cerveza, Ham in a Can, IPA
Primary: XINGU Clone, Rye P.A.
2ndary: Low Gluten IPA, Bourbon Oak Aged Vanilla Porter
Kegged: Sh*tty Orange Hefe, Una Mas Cerveza, Smokin Hot Blonde, Belgian Dubbel
Next up: Una Mas Cerveza, Pecan Pie