OK, there is no adjustment in the AR gas system if you have the standard front sight tower. The US military doesn't like adjustable gas systems since bored troops will play with the adjustments. Sights included.

I'd suggest just to cover everything that you get a can of brake kleen, gum cutter or other aerosol solvent and hose out the gas tube and the gooseneck on the stripped bolt carrier. This should take care of any possible minor obstruction in the gas system.

Now then, look at the bolt. Have you got 3 gas rings? If you have just the bolt (no cam pin) in the carrier, do the gas rings have enough tension to support the weight of the bolt?

Finally, pull the recoil spring and buffer. Make sure they're correct and in good condition.

Re-read post #1 to see if I missed anything. If you bought it new, forget everything I typed above: call customer service at the factory and send that puppy back!