Get yourself a new bolt carrier assembly ASAP.
You could probably go the rest of your life with an M16 bolt carrier in your rifle and not have a problem, but it's not worth the risk!!! I had an M16 bolt carrier assembly in one of mine for many years. Reading ar15.com forums helped persuade me to play it safe.
A premium, brand new complete bolt carrier assembly from ArmaLite is a paltry $110. Compare that to the expenses you would incur defending yourself against the weight of the federal government. You would probably stay out of prison, but it would cost you thousands.
If you really want to go cheap the bolt carrier body is just $60, add $5 for a firing pin, reuse the rest and you're good to go. [url]http://www.armalite.com/sales/catalog/components/boltcarrier.htm[/url]