AR lower magwell thickness.

I’ve noticed when comparing the dimensions of one of my Aero Precision lowers to my Colt lower that the wall thickness on the Aero especially at the front half circle cut out is noticeably thinner then on my Colt. Does this look normal and in spec or should I be worried? The lower does function without any issues but I wasn’t sure if I should worry about the durability or if it’s normal.

Left the Aero lower, Right the Colt.

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Here the Colt is on the left and the Aero on the right.


Regular Member
Oh, that's a whole new topic! But I'll say Mitutoyo for digital, Starrett for dial. I am not familiar with the accuracy/repeatability of lower cost ones, but suspect there's one from Brownells or whatever (but probably NOT Harbor Freight) that will do. Anyone?