And there you have it... what you are really saying is that YOU can't consistantly shoot your gun and get MOA or sub-MOA results. That is not the same thing as saying that THE GUN is not capable of consistently shooting sub-MOA groups.
I personally can't shoot sub-MOA groups every time I shoot (not with any gun)... I just don't have that capability anymore. But that has nothing to do with the rifle being used it has to do with a measure of MY ability. When we talk about a rifle being a sub-MOA rifle, we are saying that the hardware itself is capable of consitently shooting sub-MOA size groups with the right ammunition AND without the external effects of the shooter... remove the shooter from the equation. When we test the guns we use a rest to isolate the gun as much as possible and to make each and ever shot as repeatable as we possibly can... we try as much as possible to eliminate any outside influence from the shooter (movement, breathing, flinching, etc.). That way we get a true and accurate measure of what the rifle itself is capable of doing. That is what matters... because if the 'best' the rifle can do is (for example) 4 MOA then no matter how good the shooter is he'll never get better than 4 MOA results (usually worse because he can't hold perfect ever time).
Ammunition will also play a huge factor... different ammo will get different results (group sizes), each rifle will tend to have a specific ammunition (bullet weight, type, brand, etc.) that it likes best and that produces the best results for that rifle (for that barrel)... just because brand 'X' works well in one rifle doesn't mean it's the best performing ammo for another brand of rifle or even for the same brand of rifle... it's really a situation of each barrel having it's own preferences and that's why we will normally test fire the guns using 3 or more brands of ammo to see which gets us the best results.
Mark