question on buis

[calixt0]

Hello all,
I went out and shot my new ar last weekend and the buis had to be used all the way to the left to get it to zero at 100 yrds. I took them off to check the rails and they are tight However the buis are UTG. what is the chance that the cheap buis are the problem compared to the front site (mounted on the gas block) being slightly canted to the left?

any thoughts?

shaun

[dchang0]

It's more likely that the front sight is canted.

[berg]

What brand of upper and what type of front sight?

[calixt0]

question

What brand of upper and what type of front sight?

upper is DPMS

Sight is UTG

[Josh3239]

UTG.... you get what you pay for. I had to learn that the hard way.

[maxicon]

This is fairly easy to check. While quality control isn't the strong point on Chinese gear, it doesn't mean they're automatically bad.

With the sight zeroed, put a square or reasonably precise metal ruler centered on the rail and use it as a reference for the aperture. If the aperture is centered above the rail, but is offset in the BUIS, this means the BUIS isn't manufactured right or isn't centered on the rail.

If the sight aperture doesn't line up with the ruler (that is, the aperture isn't centered over the rail), then the problem is with the front sight position (canted sight, barrel not straight, whatever).

Likewise, if you center the aperture in the sight body and that also centers it above the rail, your BUIS is OK. If it's centered in the sight body and offset above the rail, the BUIS is off.

[PatriotnMore]

^ excellent advise.