I will post a short reply to the above post with my opinions on the subjects that have been mentioned. I do this as an opinion only and hope to avoid any arguement.
5.56 ammo vs .223 ammo is about 10k PSI chamber pressure difference. If you are shooting Wolf 5.56 steel case ammo and have to lube it to get it out of the chamber,
quit shooting it.
If you are shooting Wolf .223 steel case ammo and have to use very minor or trace amounts of imperial sizing lube on the neck only to get it out of your chamber, you are relieving some stress (steel on steel) and should not hurt yourself or your barrel.
Some brass cases are lubed prior to being fired on purpose. If you are not familiar with these purposes, I encourage you to use caution. Chamber pressures can dramatically increase as lube, even minute amounts, can manipulate case expansion. A similar, but somewhat less dramatic example, is the dent found in case shoulders when sizing bottle neck cases with too much lube.
I would shoot steel case ammo in a cheapy $100 gun or if nothing else was available.
I will not ever shoot steel case ammo in any of my guns as long as I have access to brass (or even aluminum..ewww..choke) cased ammunition.
This is just my opinion of the steel cases that too many shooters at my club (and lots of other places) leave littering the range.
Steve