Two points, Chris Rock is surrounded by armed body guards, so the blood can be on THEIR hands, not his. He can be as sanctimonious about guns and ammo as the Resident of the United States is because he never has to actually touch a gun.
Second, ammo might be cheap, but it isn't plentiful (which I know is a dichotomy). You can rarely find what you need on the shelves. I worked part time at a Bass Pro Shops from 07 - 14, so I've seen it all. Every time that there was a mass shooting, when Obama got elected, if a politician mentioned gun control, there were lines around the block for gun and ammo purchases. There was even a point where the federal government was stockpiling ammo just to keep it out of civilians' hands. Have you seen the stock market reports lately? Who's stocks are rising the fastest?