For the most part, we here at the trouble-shooting forum are knee deep in modifying or tweaking parts that we often total forget the factory should be fixing even the simplest of problems.
MJailme,
The one thing that I will suggest is before you go to all the effect of sending the rifle back; you take a minute and check the key screws (the two Allen ones) on the carrier to make sure they are tight.
Often with bushmasters, the key is loose, and the gas leak between the key and carrier is the sole problem with the rifle. As for the problems most seen with the users, the failure to Use CLP* to both clean and lube the rifle has got to be at the top of the list.
*BreakfreeCLP is one of the many different types of CLP offered, and about the easiest one to find.
P.S. Welcome both of you to the site.