Brand New AR-15 Extraction failure

[boxxman]

I recently bought a brand new AR-15 upper from del-ton, put approx. 20 rounds or PMC 55gr FMJ through it to get a zero. I then switched over to Hornady 55gr Vmax molycoated hunting ammo to see how my rifle liked it. IT DID NOT LIKE IT. Fired the first round, and the spent brass was not extracted, bolt fed the next round into the spent brass. I SPORTS, had to PULL HARD on the T-handle to get the bolt to the rear. lathered rinsed repeated. same with the other Two rounds. Cleaned bolt, BCG, chamber, barrel, EXTRACTOR... didn't See any visual signs of... anything. I am wondering if i need to send this upper back to del-ton, or if this is possibly just an ammunition issue. Thanks for any support/comments.