Many people don't realize the mechanics of what is happening with steel cases in a .223.
If you put a 7.62x39 round next to a .223, what do you notice other than the diameter of the round? You notice that the .223 is more cylindrical, while the 7.62x39 is more conical (roll it on a flat surface to see it dramatically).
The Russians used the conical shape to ensure smooth loading in any condition chamber. A .223 requires a cleaner chamber.
In order to avoid problems in a .223, plinkers and combat guns should have a military chamber that is looser. But with a less conical (more cylindrical) shape, you can only make it just ~so~ loose and still expect to have a safe headspace, etc.
Just like dropping a cone into a cone shaped hole vs dropping a piston into a perfect cylinder hole, a 7.62x39 round will load easier than a .223.
What this means is that lacquer won't hurt a 7.62 chamber until it gets SO bad. It will affect a .223 rifle much sooner. Milspec chambers, such as found in the base Mini-14, and in good, base Bushmasters and Colts, will be OK, at least for a while, and match chamber .223's should stay AWAY from this ammo.
That's my 2 cents.