Re-run the rig, and before you start the run, make sure to lube the B/C on the heaver lube side with CLP (both inside and out of the B/C).


At each 100 round mark, pull the charging handle back about 1" until you see the gas rings move forward of the carrier exhaust ports on the side of the carrier, add in a good douse of CLP into the gas chamber section of the carrier (will migrate to the rest of the bearing areas during live fire), use the FA to make sure that the bolt is fully locked home and go on shooting.

This should hold you to around the 300 round mark, then pull the B/C, give the chamber a good chamber brush cleaning with CLP, run a few dry patches to get the chamber and bore dry while still at the range, re-lube the carrier in and out with fresh CLP (don't bother removing the old CLP on the carrier) and solder on for another 300 rounds.

Once you hit around the 1K mark with live round through the rig with  cleanings along the way, should be able to stretch the gas chamber re-lubing out to 200 to 300 rounds of steel coated ammo.
Note, if the rifle starts to get sluggish on cycling out spent rounds before the normal -relube mark, add some more CLP into the carrier gas chamber (with the CH slightly pulled back to get the CLP behind the rings).


And again, on rigs that have self polished in , have run steel coated ammo by the pallets without cleaning. Relubing on the other hand, lets just say that with all the new CLP being introduced along the way without cleaning the parts every few hundred rounds, the rigs where a bit shimmy in the end.

Old_Painless suggested that you DRY out the chamber to prevent high pressure against the bolt face.

Chambers should be run dry.  What we teach in armorer courses is that after cleaning is to run a patch of denatured alcohol through the chamber to make sure that all solvent and lubricant is removed.  Dry patching alone may not remove enough, as if there is any solvent or lube in the microscopic pores of the chamber, then when it gets hot the lube can leach out and cause casings to stick.    

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123

Might have to wait until the chamber loosens up (side wall cross dimensions) a bit through cleanings and dry firings with the brass case ammo, but give it another go with the rifle cleaned again and the steel coated cases, and this time try using a small spray can of BreakfreeCLP to clean, then lube the upper receiver bearing surfaces on the wetter side (shot of CLP on the inside and out of the B/C to coat them, then no ammo cycle the B/C in the upper a few times to migrate the CLP off it to the upper receiver bearing areas).

If you do start to stick cases again before the 150rnd mark/relube point, Just pull the B/C, hit the chamber with a chamber brush and quick shot of BreakfreeCLP on the brush to give it a quick scrub, then dry the chamber with a 30 cal mop afterwards while still at the range.

On the positive note, the extractor is not being ripped off the rim, so we know that the extractor and spring a fine.

You can polish the chamber to a mirror shine and see if that helps.  Check the headspace as I suggested before.  You can also cast the chamber to give you a good view of what it looks like.  

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123