The steel case itself will not affect the barrel but the chamber.  The case should not extend into the rifled part of the barrel past the throat.  And of all the weapons that I would think would not be subject to any concern in this matter, the AK and SKS are on top of the list.  Most of that steel ammo was probably made in Russian plants for russian weapons...I think you will be fine...just clean for copper fouling like you would for any other copper jacketed round and you should be fine...have fun shooting...

what are you looking for a CT for?  I generally just google a CT model number and find the cheapest one I can that has some varied and mostly positive reviews..

You should be fine using steel cased in an AK or SKS.   I usually avoid it in things like AR's or pistols though.   

It's not the weapon that's designed for steel cases per se, but the round does or does not lend itself well to the use of steel.

Brass is more elastic than steel.  As such, when a brass round is fired and expands under pressure, it mostly returns to its original shape.  Steel isn't as elastic, so under pressure it expands and stays that way.  This creates a problem for rounds that do not taper very much as they kind of wedge into the chamber. 

In a 5.56 the case expands, stays expanded, wears on the chamber as it's being dragged out, and can stick.  This would be the same for 7.62x51 (.308) or any mostly straight-walled case.

If you look at a 7.62x39 in comparison, you'll see that the taper is considerably sharper.  That being that case, it is more easily extracted, produces less wear on the chamber, and is unlikely to become stuck.

Basically, it's the round, not the weapon.  So in any weapon that is chambered in 7.62x39, be it an AR, SKS, AK, whatever, you'll be fine with steel.


Beyond that, the case material isn't relevant as it never comes into contact with the barrel (as has been point out already).


-T.

T steered you right on the case taper thing hrswhsprr, but I'm curious-

I will keep loading my brass cases (7.62x39) for varmint shooting and use the steel for letting off steam.

Do you have a bolt action 7.62X39?  If not, I'm curious as to the why on the brass cased ammo, as every semi I have, and most I've seen in the caliber, mangle brass cases pretty well during  ejection.  To the point I'd be very nervous about reloading them.