In 2006 I remember the 100 round shotgun target loads at walmart were $12-$14.
Today they are nearly double that.
Inflation typically makes things cost double every 20 years. It has been nowhere near 20 years.
Material costs are not that much higher.
The market has changed from one where workers could demand things from employers to one where employers can get away with giving less to workers that want jobs. So employee costs are actually down, not up, making it cheaper to operate.
While transportation costs have gone up due to higher fuel costs.
So really they should not cost that much more.
I would say they charge more because they can. It is probably being realized as profit. Not because they have to charge more to make the same percentage of profit as they did, but because they can now get away with higher profits in a market that will still buy ammo anyways. The gun nuts that were buying rabidly around the Obama election showed that they can get away with making quite a bit more profit, and that some of the market is so nuts that all they have to do is wait and people will still eventually buy what is made, and sometimes even buy more because they panic when it goes up.
Then they can drop it back down slightly and people will buy massive quantities to hoard, even though in reality it still costs more than it should.
Take it up even further, then put on a sale for slightly less and people will rush to buy it even if you are still ripping them off compared to old profit margins.
All of this makes for a market where the customer has pretty much told the manufacturers they can act similar to the oil companies, and people will still buy their product. They can go up 60% in price for awhile, then drop it back down 10-20% and people think they are getting a great deal with their short attention spans.
Since the last election the number and percentage of new owners of firearms is also greatly increased. So the market is larger. So there is even more customers buying the products from a similar number of manufacturers. Which certainly makes them feel even more secure in profiting and moving their product even at increased prices.