Cowardice by Obama--and courage by those in the US that opposed it. The internals had to be horrendous on this, thanks to such groups as the Sipsey Street Irregulars, Gun Owners of America, the National Rifle Association, and others.
For DUmb**** lurkers, the Second Amendment says nothing about hunting, or even the shooting sports. The sole purpose of the Second Amendment is to make the government afraid of its' citizens. Then, there is liberty. If the citizens are afraid of the government, there is tyranny.