If it's a really cheap unit, and it came with a buffer, my first thought is that it may be one of the sleazeball buffers that I've seen w/other el cheapo telestocks.
A properly contructed buffer will have steel weights alternating w/ thin rubberized discs, and you can feel the weights moving back and forth somewhat, when you shake the thing back and forth. Many of the el cheapos just have a bunch of lead shot in there for weight, but that totally screws up the recoil cycle of the action. That, combined with a POSSIBLE need for a heavier extractor spring, can really screw up the action cycle of a carbine type.
See if you can borrow a Colt, Rock River or bushmaster buffer from someone, or just go ahead and spend the bucks for a good name brand buffer, and see if that doesn't help matters[:D]
And yes, Olympic ammo doesn't have the best rep in the world, and might be contributing to the problem; tho I'd doubt it's the promary cause.