Don't expect the carbon to be the same as a standard AR15, in general they are not considered to be of high quality.  From an EOD perspective, old dynamite found in a mine shaft versus new blocks of C4.  Both are explosive, but one you are going to trust a lot more than the other.  I'm honestly not sure why Bushmaster still makes those aside from being able to do it cheaply.  On a brighter note, in the world of haves and have nots, at least you have a firearm. Aside from snapping stocks, one of the other issues seen is bullets gouging into the receiver just underneath the barrel extension.  Once they start to make a hole, the weapon quickly becomes inop as it won't feed.  A simple fix for this would have been M4 style feedramps into the polymer, but I think it would have made it too thin and have created more problems.  It is just something to watch out for.  I'm not sure if Bushmaster will cover that, everyone I know has just traded them in towards regular AR15s eventually if they used them for training or as regular shooters.  

Get out to The Arsenal often?