The 1st firing of 150+ rounds were w/o problem. The next had persistent fte's and a very short secession. I did a through cleaning and oiling and on another day, Same continued problem. 40 out of 100 rounds, 3 different brands of ammo including Winchester Whitebox and federal, were fte. I used a caliper to mic the spent brass and found about .002 to .003 in. runout, also present and caused by the chamber. I suspect the extractor arm allows slight rotation and the HOT out of round brass drags and causes a jam in the out of round chamber and/or the arm slips off leaving the casing jammed between the breach and port. The cause for the out of round chamber MAY be inadequate Metallurgical heat treating of the barrel, to allow warpage after the 1st real heating and cooling cycle. This may be worsened by the asymmetrical breach with ramp.
I guess I will try to talk with a Kel Tec tech rep to get an RMA for repair with a new Proper Barrel.