from hands on experience with a few hundred thousands rounds of both(class III belt fed guns eat it pretty fast)

steel cases can cause excessive wear and tear, the lacquer on it has been known to gun things up and has broke more than its share of firing pins from it!

I will NOT use steel case ammo in any GOOD tight chambered gun, or gun of higher tolerances and want to keep them that way!
it can EAT away chambers, as steel is harder than brass and after a LOT of expansions ina chamber, it wears faster due to such!

things like most 9 mm-45 and so on pistols meant for so so accuracy(not match grade) they work fine
rifles like AK's they work well, as they just have rather sloppy tolerances
but I will NOT use it in any AR or like (m-16) I have seen way too many issue happen while using it!
YES countless folks use it problem free, but many DON"T
and I don;t care to risk it anymore!

Back to the coating on them to prevent rusting, it can get damaged and over time rust!( I worked in a UV Lacquer flash curing process for 15+ yrs, curing in a matter of hundredths of a second,, and void happen in the coating process from many reasons, from oils or or like on cases(even finger prints an cause them) on metal before coating, air bubbles, contamination from dust to debris) ,its never a100% perfect ALL the time!) same can happen with over coatings of SOME cases in a run!


all depends on how long your thinking of keeping it maybe on this though!
most are sealed up pretty good in military grade cans and cases, some are NOT as good!
I have also seen some primer issues over the yrs too, but not THAT common,
but the lacquer on things will again coat and can cause sticking of firing pins and even cause them to build up
HOW many rounds to make this a issue, varies from MY experience and the tighter again tolerance on the weapon, the faster it seems to show up!


its cheap for a reason folks