I have the Gen 1 and the Gen 2. I like the Gen 2 on the Athlon Argos a bit more, due to it having the factory zero stop for elevation.
The optics are "good", but certainly not as clear as More Expensive offerings. That said, I have one of them mounted on a 6.5 CM, and have no problem hitting a 400 meter gong which is 6 inches in diameter with repeatability.
All of the Argos models suffer from a very tiny eye-box at magnifications higher than 15. But then, for 400 yards you won't need magnification over 15 for that use. The "box test" on both of my Argos scopes was perfect and reliable. The parallax on both was rock solid. I purchased a snail for one of them, and calibrated it at known distances (factory parallax numbers are off on almost all scopes, especially if you adjust the eyepiece to match your personal preferences on vision). I included my elevation clicks on what was written on the snail. This made shooting easy. I just adjust the parallax until the "head-bob" test is perfect, look at the wheel, adjust elevation for the specified clicks, and send it. I have had no need to re-adjust my scope between trips to the range. But then, I don't bounce my gun around in the bed of a truck. Perhaps with rougher treatment, this would not be the case.