It has not changed
When gas was at .17 and Cigarettes were about the same by the carton....
Today gas is at $3.50 or so, and by the carton, cigarettes are a bit higher... but so are the taxes on them...
The comex has copper priced at $4.4167 as I write this, this is up from about $3.50 6 months ago, and up about .45 cents from a year ago.. recent five year low was $1.20 from Oct of 08 to about march of 09...
Copper is the base metal for brass, as well as bullet jackets.
Lead is currently at a near all time high of $1.22, its market ups and down have paralleled copper and other metal commodities. (kitcobase.com will give you current world non-ferrous metal prices in real time as well as historical charts)
As stated, the major cause of price increases is the devaluation of the US Dollar, and world demand. China and India being the major consumers of red metals (brass and copper) And there will always be an excuse jump in for speculators to bump the market... Mine disaster in Chile, Earthquake in Japan, Strike in copper mine in Bugtoot where ever...
Bottom line... Buy it before the suppliers figure out it ain't getting better and they bump the prices. When you spot a deal on ammo or components..GET IT..
I retired as a Police Officer a few years ago, now, I am in the Scrap Metal business... I have to follow this trend hourly..