Well, your first move would be to watch the documentary/film by Michael Moore entitled Bowling for Columbine. I have included the link to the enotes section regarding this film below. It is an excellent and hilarious documentary regarding the gun culture in the USA, and it features a number of excellent scenes that you could use as the basis of a satirical story. The first, and my personal favourite, is when Michael Moore goes to open a bank account to take advantage of a special offer which gives him a free gun if he opens an account with them. They actually give him a choice of guns right there in the bank with bullets and everything! Hilarious, but also rather disturbing. He then goes on to investigate what happened in the Columbine Highschool Shooting and some of the issues surrounding that. Lots of scope for satire!