AR-15 Stripped Lower Prep?

briansmithwins said:

Drills aren't precise. A reamer would be much more precise way of enlarging holes and gauge pins would be better for checking hole sizes...

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Was hoping someone would come here. Even with a complete drill index, it's a drill. You want precise and round you don't use a drill, but a reamer. Inspect with gauge pins, not cutting tools.

If anyone wants to be extra cautious or precise, go ahead, but then Be Extra Cautious And Precise. Don't use the wrong tool for a high-precision job.

I only had to do anything to one lower...an Anderson. A drill bill through the take down detent hole to open it up properly

shoobe01 said:

Don't use the wrong tool for a high-precision job.

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There are no holes in an AR lower which are “high precision”.

Varminterror said:

There are no holes in an AR lower which are “high precision”.

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Well, I meant if you are trying to measure with (or improve yourself to) great precision.

Carpentry is done fairly rough (even called "rough in" work sometimes), but no one buys tape measures that are just okay, with 1/4" inaccuracy over 10 ft distances because it's "not precision work."

Just a use the right tool for the job comment.

Since “the job” pertinent to this thread is prepping AR lowers - not a high precision task - a drill bit or a bit of pin-stock with lapping compound can easily be “the right tool.”

For knocking off burrs inside detent holes, a drill bit in the hand usually works. Doesn't even have to be in the drill most of the time. If the whole were the wrong size, wrong place, or crooked I would consider a high precision reamer. But for just some sloppy cleanup after the holes were made, not necessary. And the biggest manufacturing flaw I ever ran into with an AR lower (Anderson) was the pistol grip hole was improperly tapped. So I had to track down the right tap for the grip screw I had and re-do it.