I have used Wolf brand ammunition for years without trouble, but I had only used it in my SKS or AK-47. I never tried steel cased ammo such as Wolf brand in any other gun until recently. A few weeks ago, I tried it in my AR-15 for the first time. My gun has been cryo'd and I figured it wouldn't hurt to just pound a few through it. My Colt ate the stuff up without a single problem. It did however make my gun dirtier than usual and required a bit more cleaning. I did not notice wear or damage to my gun with about 200 rounds of the steel stuff.
I have even tried some various brands of steel ammo in pistols lately. Kevin Davis gave me a few boxes of Herter's steel cased ammo in 9mm and .40 S&W. I shot all 5 boxes and did not have any of the trouble Kevin complained of. Maybe I was just lucky! I also shot some Tulammo 9mm and .40 S&W with no issues to report other than Tulammo and Herter's ran dirtier in my gun than the American ammo I am used to shooting. It's been my experience that anything that comes from overseas makes your gun dirtier than our own domestic ammo. European gun powder seems to not have the same quality as ours. Maybe they do not have the same quality controls our producers have. Of course I will say that some of our cheaper lines of ammo do run dirtier than our higher end ammunition. But it seems that our cheaper stuff still runs cleaner than the overseas stuff.
The downsides are:
Steel cased ammo runs dirty
Some are laquer covered and it can melt off and gum up in your gun
Steel cases cannot be reloaded
Surplus stuff can be corrosive
Some guns are not designed for steel cases and can wear faster