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As far as my AR goes, the gas blowback works fine. I haven't had a malfunction since I've had it, for about 500 rounds (true, that's not a lot) you personally really don't get dirty as a shooter, other than just range dust from being outside, your hands get dirty from loading magazines though like every other gun.

So you probably are correct in the last 2 assumptions, and yes I'm fairly certain it is a blow back design, with that said, if you're gonna burn triple digits of dollars to perform what I would consider a minor upgrade at best, which you would probably have to do with every new upper you get, it would be more cost-efficient to spend that money on practice ammo, or a free float barrel, or fluted, or a longer barrel, or a higher quality bolt assembly, etc.

But, I have not looked into the gas system really, all I know is from shooting experience, no research. The AR does get fairly dirty, and since it's all black it can be easy to miss spots, which if done over and over can lead to jams and what-not, but I'd rather take the time and clean the weapon properly then spend good cash on a system that's not broken.