im not too sure about kirenex. but i know some clones are really good. like my friends JG M4A1 and then i used to have a A&K M4-S and comparing it to the TM it worked just as good and it was $450 and the TM was $710.
The Lord God Sytema shall smite thee by drowning thee in a sea of off-spec BBs. - mcguyver