AR15 lower build - safety detent won't fit

[GTSteve03]

Starting finally building my second AR15 lower tonight and of course ran into an issue.

Using an Aero Precision lower and PSA EPT lpk. Got to the safety selector install. Went to drop the safety detent down the hole in the receiver and it doesn't fit. Yes, I did put it in small side first. Seems like either the detent is barely too wide or the hole is slightly small.

What's the best way to fix this? I've seen suggestions to use a 1/8 drill bit by hand to try and smooth out the hole, or to put the detent into a drill and use sandpaper to polish it down. Any other ideas?

 

[Plinker66]

Fourth Armory prolly has a pin in stock yours looks funny from here.

 

[Greybeard]

I normally run a number 40 (or is it a 30) drill bit down before anything. I think when they coat the lower a small amount of coating gets into everything. I also run a tap in the threads for the pistol grip, just to clean up the threads.
I am sure other do it a little different but that's what works for me.

 

[Duce4trey]

looking at that pic, that detent looks outta place.

I would buy/ try a new one.
If the same results happen then my guess would be that the hole is not in spec.

 

[Greybeard]

I checked one of my blanks, and the pin hole is stepped down. First step is about 1/8 inch deep by drill diam number 22. Remaining hole uses a number 30 (about 1/8 in). I would clean out the second step, I think you just have a little build up of coating in there.
If need I have the mil spec plans for the lower, would just need to figure out where I put them.
Hope this helps.

 

[jeep78]

Having a new, sharp set of drill bits on hand when doing gun work is always a good idea. You are not drilling the holes, but cleaning them out to proper dimension.

Download you a copy of the AR15 blueprint so you have the proper dimensions when you start measuring . Drill rod is great for checking hole size (the back end of a NEW bit).

 

[GTSteve03]

Thanks for the suggestions. Will definitely get a new drill bit and try that first.

 

[jeep78]

And you spin the bit between your fingers, not in a drill motor.

 

[GTSteve03]

Looks like a bad detent. Used a brand new 1/8 bit, I had to clean a little of the finish out of the hole to get it through. But the detent still won't fit.

It's a shame as the EPT trigger seems nice but I can't try it out til I get this stupid detent in.

 

[Greybeard]

Boy that stinks, I think you can pick one up from psa, or a local smith for about a buck. I would still mic it just to see what size it is. I think around .120 would be about right, or lightly sand it.