I bought a set of BUIS from Marstar and they refused to sight in, even when fuly a adjusted for elevation. Marstar's staff gave me several suggestions for lowering the mount, including trimming the front sight post. When this didn't work, they mounted a similar set, did a range test and found that the front iron sat a half inch higher than the rear iron.

They've issued me an RMA, despite minor damage from tightening the screws and shaving the front sight post.

Marstar responded to my emails quickly and was very helpful throughout. I'm posting this as a thank you to Marstar for their fine customer service, and as a short read for anyone doubting Marstar due to unwarranted posts criticizing their service.

Cheers,
Khoeep