i stand behind my COLT, i understand what HK45 is saying, differant upper retension pin sizes, etc. and armalite has incredible service and a great web site! , and i truly believe any AR is better than no AR, however no $ of mine will ever pay for any other kind of AR than COLT. my mags r COLT, its COLT! 4 no other reasons than its what i own and i love it! even if theres something better, its COLT. kinda like the anti .270WSM .7mmWSM and .300WSM people, if its new, maybe even better, i want nothing 2 do w/it. its COLT baby! lol