The 'tier' thing (the 'chart', etc.) rates different AR's against Colts TDP (technical data package) which provides complete specifications for the M4 carbine (this TDP is part of Military Specification MIL-C-70559). A civilian M4 pattern carbine cannot meet the TDP in its entirety as we've no access to current production select fire weapons and 14.5" barrels (with or without a standard threaded muzzle device) require a NFA tax stamp. They may, however, follow all other specifications in the TDP. It is on this majority of the TDP specs that 'the chart' categorizes weapons and by this specification that a weapons 'tier' is determined. Some view this categorization as elitism or snobbery and I suspect this is the case with some folks who frequent AR related forums (wearing their weapons adherence to the TDP as a status symbol). Snobbery/elitism isn't the reason that 'the chart' exists or for weapons to be classified as 'tier 1', 'tier 2', etc. They exist so that those who deem adherence to the TDP an important factor in choosing an AR have relevant data to work with - nothing more. Keep in mind that the M4/M16 platform is the standard issue carbine for our armed forces. For these folks durability and reliability are crucial - truly a matter of life and death. The TDP a set of standards and specifications designed to produce and ensure the most consistently durable and reliable weapon possible for this weapon platform.

Should this matter to you and I? I'd say that depends on one's intended use for their AR(s). If I were a law enforcement officer and I were purchasing an AR to be used as a duty carbine I would definitely find 'the chart' (or, more specifically, its data points) useful in selecting a carbine. In this case a 'tier 1' AR (as determined by its adherence to the TDP) would be a wise choice as my life may well depend on that carbines ability to perform reliably. This is true for those who run their AR's hard (those who attend carbine courses and train in the same manner - thousands of rounds per month) as this is where an AR is more likely to fail. Those AR's built to the TDP's standards are, generally speaking, less likely to fail when being run hard.

Short version - these qualifiers do not exist for bragging rights. They serve a purpose. It's up to the individual AR owner to decide for him or herself whether adherence to the TDP is an important factor or not. A great many AR's are manufactured with deviations from the TDP and function flawlessly for their owners in their intended application. It's not a competition or a popularity contest - it's simply a set of specifications (and a means by which to measure a given manufacturers AR against that specification).

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