Surprisingly I haven't been able to find very much about these on AR15.com with the search function.  So how do these hold up?  I know I can't expect the best of the best given the price, but can these be considered reliable backup sights?

I run a MBUS rear backup sight on my DPMS sportical 7.62X51 with no problems through 200 rounds my front sight is a Midwest Industries HK style Gas Block flip up. For what it's worth I have a Front MBUS the only reason why I'm not using it is becasue I didn't do my research first. They are not meant for gas block applications the elevation won't go high enough becasue of the difference in the sight planes. But to answer your question the elevation adjustment is staked in place with one of two provided polymer stakes the instructions state to ensure that your zero is set prior to 'staking' you front sight adjustmen. Hope that helps.

I run'em front & rear on my LMT Piston.  Excellent performance and holds zero.

I have the rears on all my AR's. They have taken a beating & hold zero fine.
The only complaint I have found is I had to dial in a lot more left windage then other sights. The peep hole is almost all the way left.  And I know it's not my uppers, because they all wound up being this way.  I guess is something in the way the sight is designed.

I have the same issue with having to adjust them way left. Other than that they work just fine.

mine is way left as well... weird, i thought it was just becuase I am lefty.


Other wise it holds zero just fine I have mine on my 3gun/HD rifle and havent had any problems with it.

another +1 wayyyyy left for mine too .... sounds like a common issue.

I just went and checked mine and my rear MBUS with Midwest Industries Flip Up Front sight is just slightly left of center. I derive my sight picture using the nose to Charging Handle Jaw/Cheek to buffer tube/stock method. I don't know if this sight picture alignment changes the adjustment on my rear sight or if it is the combination Front and Rear MBUS that moves the windage to the extreme Left.