Ok for a budget / short distamce build rely on it for an optic. - American Tactical Imports AR-15 Stripped Poly Hybrid Upper Receiver

I bought a couple of these to test. They are not compatible with some items like a Dolos kit or heavier optics. I think it’s hit or miss on quality. Fitment for same barrel was different on each. Agree with other reviews on grade of materials, but they do hold up to heavy loads. I ran a 458 socom on one, 223 and 300AAC. No issues other than can’t hold a zero for anything past 50 yds. I worked and worked on everything other than swapping back to AL upper. I tried several optics and with a romeo5 I could keep groups well enough at short distance to count, then just went to BUIS. But when mounting a scope on it, it’s just not stable enough especially as your barrel warms to hold a solid zero. Only swap I made was back to AL and new dope on my glass, tack driving again. It was just this upper.