I have a customer who is wanting me to drill and tap some 1/2-13 holes in some AR 400. They are for a quick attach bucket for a loader. The 1/2-13 holes will be for securing the pins.

I have drilled AR400 before but never taped it. What you guys got for me? What kind of tap would work best, carbide? sprial flute? And help would be great!!

Thanks in advance Justin

None
You are awesome just for drilling it!
Then again, I have done a bit of machining on AR
I typically punch or plasma AR wherever possible.
If someone asked me to tap it, I would EDM tap or thread mill (if I could rig it into my machines) OR I would plasma a hole and weld a nut on (best option).

I have never delt with AR400, but in Inconnel, I have used the OSG TiCN coated plug taps. Ive personally hand tapped 300M with these taps with a 5/8-18 tap. The EXO List 300 series TiCN is whatcha might try.