I kind of think of the AR10 the same way I think of 1911s. Ones that work are a thing of beauty, but you can't count on every one to work. Can't just step up to a fireing line with ten anonymous 1911s and expect them all to work 100%. Additionaly, they are tuned machines that will always require more upkeep than other designs. I'm not sure that I'd go so far as to call them "range toys", the Canadian military certainly doesn't, but each one should be treated as an individual and vetted as such.