The copper mining industry is a little more complicated than just producing more to meet the demand.
The "stock piles" are different grade ores & typically blended with higher & lower Copper contents to provide a consistent feed into the solvent extraction process & ultimately end up into a Electro Winning tank house where the plating occurs.
Unfortunately each "plant" is designed to consume a determined blend feed at a constant volume to remain in business. To simply increase production is not possible without upgrading your plant at a major cost, or reagent imbalance (additional cost) to consume the input. Feeding lower grades of ore increases cost of manufacturing & ultimately causes mines to shut down when the Copper price dips too low. Never mind quality issues. Consuming too much of the far les available high grade ore, reduces the life of mine.
Your only solution to really increase output is to weigh up your options for an upgrade or risk investing into green fields which is a complicated & costly business altogether. Then you have to hope & pray the market doesn't drop below your manufacturing cost again.
Copper prices over the recent past have been quite low in comparison to when the prices were almost double a few years back, we didn't see much of the price fluctuations in the ammunition prices.(besides that it only goes up over time) The reasons are numerous, though one of the reason is due to the relatively "small" consumption for the public ammunition production market where the offset will be traded at much higher margins & the fluctuations can be "absorbed" in comparison to the larger consuming markets directly experience the effects where every $ counts & the price reflects to the end user.
I more rather have a problem with the quality of the Copper consumed to produce ammunition that could jeopardize us as hunters.
Not all Copper are produced equally.
Some current quality producers may opt for lower grade Copper to save or source from different regions /traders where certain elements like lead (Pb), Cobalt (Co), Iron (Fe), Sulphur (S) & silica (Si) might be more prevalent, but the price is "right" due to lower cost of logistics or other trade agreements.
The copper may be 99.9% Cu and it gets worse as the percentage drops, these impurities / alloys affects the nature of Cu. The am elements tends to cause the Cu to be harder & brittle.
I cannot comment on the ammunitions manufacturing end, I don't know if some ammunition manufacturers have a special alloy blend, but I did notice the oxidation patterns on recovered cups from a big and much debated brand on this forum... it turned brown like typical iron rust with a very small amount of green oxidation.
This tells me that the material is definitely not quality or pure Copper & it wouldn't surprise me that the cost saving by "blending" or sourcing crap has already started. I also want to point to this as the primary reason for poor bonding & bullet failures under discussion.
I hope the current quality manufacturers doesn't change their sources or grade of material to save cost.