Put together this Aero blem lower yesterday, and the rear pin is so tight, that I've got to use punch/hammer to take it in or out. Hole appears to be slightly too low. I tried to get a good pic of the space below the pin. Should I file the top of the hole slightly, or is there a better way? Guess I know where the blem is on this lower. Upper works fine on 3 other lowers.
I would try another upper on that lower to see if it is in fact the lower. I had the same problem on a build I did for my grandson and it ended up being the rear lug on the upper that was the problem. I filed the hole in the upper lug to remedy the problem.
If I were to file the hole, instead of a rat tail file that is tapered from end to end, I would use a chain saw file that is as close as possible to the diameter of the pin. Chain saw files are the same diameter end to end, and would help keep the hole as straight as possible using a file.
Any chance you know someone with a Bridgeport that can use the correct size end mill to 'move' the top of the hole?
I would not just drill the hole oversize to make parts fit together.
aero claims blems are only cosmetic, i would call them and perhaps arrange an exchange as obviously it's not "cosmetic". their claim is everything is good except for the finish, everything else is "mil spec"
barring that you might try a quarter inch dowel and some really fine emory paper wrapped around the dowel. take down pins are supposed to be .250 inches,,,using my rusty math skills that's a quarter of an inch
In case you are not aware, Aero Precision lowers have a nylon tipped set screw that can be used to tighten any play between the upper and lower. Is this causing the tight fit?
Sometimes it's not a matter of the holes being drilled improperly but the radius of the upper/ lower not being the same where the buffer tube screws in. Shine a light through it to see if they do not mate properly there.
After 10 minutes with the file, checking and fitting often, upper and lower fit tight with no wiggle. Pin takes a good push to get out, but still doable by hand.
Had same problem on a billet 80 % ended up reeming the upper to lower but like an earlier poster said the lower is married to the upper now no wobble though
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