Holy jeez, read a newspaper.
There are several factors at play:
1) Increased demand for ammo by civilians and the military. Plenty of our Afghani and Iraqi allies are still using 7.62x39. The U.S. mil is obviously using lots of 5.56. On the civilian side, black rifles are becoming more and more popular. There are also reports of ammo hoarding out of fear of the November elections.
2) Increased demand for lead and copper, primarily by China and India. Their middle class is growing and they require lots of lead and copper for wiring, plumbing, electronics, etc. China also has a tendency to supply countries of dubious character with guns and ammo.
3) Increased cost of fuel. From the big rusty boat that ships ammo from Russia to the big brown truck that drops it off at your door, fuel costs have hit everyone. Oil hit $135 a barrel last week and diesel is well over $4 in my neck of the woods.
4) A weak dollar. The dollar's value hasn't been doing so well in the past few years and that means it takes more dollars to buy foreign goods. Most 7.62x39 ammo is foreign.