It seems as though quite a few people are having issues with mounting optics and BUIS on their flat-top uppers in regards to them canting to the left. This problem seems to effect Troy and EOTech more than any others and it has been reported on LMT, Stag, Mega, RRA, & other brands of uppers...even on Samson and I believe DD FF rails. Are all these rails just out of spec for some reason or what's going on? You'd think if it was an issue with Troy or EOTech specifically, these issues would have surfaced YEARS ago. So...WTF's going on?

The only encounter I’ve had with rails out of spec was on my M1 Sales flat top upper. This upper was bought about 4 years ago so I have no idea how they are now quality wise.

I ran into problems trying to install an ARMS Swansleeve. The upper angle of the rails required filling down to bring them into spec enough to get the Swansleeve to slide down on top of the receiver. It was basically just the anodizing I removed with very little material and haven’t had a problem since with mounting optics. Even my EOTech sat perfectly flat.