04-23-2023, 02:54 PM
js8588 Wrote:If the manufacturer's tolerances are tight enough for a thermal fit, they're likely also precise enough to not need lapping. I tend to avoid Aero and their subsidiaries whenever possible. They're all what would be considered "rack grade". Grab something OEM'ed by Zev and you won't have to worry about it.
You can quite easily tell if a thermal upper needs lapping using a .0020 feeler gauge.. After inserting the barrel in the upper, check for gaps between the upper and barrel extension lip..
High end parts are not immune to QC problems..Trust but verify..