Quote History Originally Posted By seattlephoto:
What do yall think about the rear takedown slot on the upper?
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In the early production runs, 1 out of 4 uppers had this issue... reason being that one of the four stations on our manufacturing fixtures was set about .005" too high on that feature.
Since we were just using Aero lowers and assumed "Mil-Spec" was "Mil-Spec", we ran it that way for a couple months of production and they all did fit all Aero lowers we had in stock.
However, on other brand of lowers, these 1 out of 4 ended up being too tight.
We have since adjusted the tolerances and all our uppers will now fit all lowers.
In any case, we do warranty (and have done so on several) the upper if it absolutely wont fit any lower (without filing).
Your filing job is fine though and wont hurt anything functionally short term or long term.
Your setup looks really good!