First off, wolf steel case poly ammo is not under loaded, but just loaded to 223 standards, as well at the gold too.

The differences, the poly coating on the steel ammo is not as slick at the gold cases, and this means that as the bolt is trying to pull the spent case out of the chamber while the bore still has residual pressure, the poly spent case are harder to pull out (lets just put it as more of an adhesion effect to the chamber walls).

Normally if you are both cleaning the chamber with a chamber brush and CLP by hand during cleanings (standard solvent will not dissolve the poly powderized fouling in the chamber, it has to be scrubbed out instead), and keeping the upper receiver bearing surfaces on the wetter side with CLP, you don't run into problems with the poly/lacquer coated steel case ammo.  Also to point out here, you use the wrong solvent to clean and lube the gun, and it going to cause problems in itself.  Take Hoppes products and they belong no where near the rifle.  The Hoppes copper solvent leaves behind a sticky residue (worse when it mixed with CLP, and  Hoppes gun oil has not cleaning properties in it once so every.  Bottom line, short of the barrel bore that is first cleaned with something like Sweets copper solvent, the rest of the rifle should be both cleaned, the fresh lubed with CLP.  If you need a source for CLP, walmart sells BreakfreeCLP in the large 16oz spray cans for less than $10.  Regarding Sweets, it does not require a lot of scrubbing to remove copper fouling, nor does it leave behind any coating as well.  So the bore is first cleaned, then the chamber, and the chamber fouled CLP pushed out the muzzle, will still leave enough of a short term protective coating, even when you think the chamber and bore are bone dry instead.





Now on tighter cross wall chambered barrels, or chambers that have some reamer chatter, you can run into problem, even with the above done correctly.   If the problem is just a tighter say match type cross wall chamber barrel, just firing brass case ammo and cleanings  along the way will solve the problem, since such will smooths and loosens up the chamber in around 500 rounds.

If the problem is ream chatter instead (you have scrubbed the chamber got it dry, and confirmed that the chamber walls are mirror smooth), them minor chatter can be polished out, while major chatter requires that the barrel be sent back for a replacement isntead).

To sum it up since you are only having problems with the wolf poly coated steel cases, clean the chamber with a chamber brush with CLP by hand, dry patches through the chamber and out the muzzle until you get the chamber clean (Q-tips to clean out the last of the fouling in the barrel extension void), and post a photo of the chamber wall conditions.  


This is what you should be seeing, with the chamber walls mirror smooth.


And not a chamber reamer chatter cluster fuck mess isntead,


Also, every 200 to 250 rounds through the rig, pull back on the charging handle just enough to get the bolt rings to pass forward behind the carrier exhaust ports, give a quick shot of CLP into the carrier exhaust port, use the F/A to lock the bolt back up and keep on shooting.  These few drops of CLP during the quick spray blast, will migrate through the upper receiver to re-coat the bearing areas as the rifle is cycling, and the cleaning agent in CLP will go to town at dissolving the powder fouling to keep the rifle from choking out.  Note; small amount of the CLP will be transfered to the cases on loading, and this small amount are enough to help keep the chamber from fouling out as well.

Hence if you upper looks like this, your not using enough CLP to start with, or re-lubing often enough isntead.