AR barrel threads: 1/2-28?

I'm making an extended flash suppressor for my varmint AR, to eliminate muzzle flash in my line of sight when it's dark or dusk. I've got the stock turned down to 1 1/2" X 6" and centered. I'd like to drill the bore ("R" drill) and the counterbore and tap it all in one operation, without breaking the setup in the drillpress. I've mic'ed it and checked it with pitch guages and come up with 1/2-28. Can someone verify this so I dont tap it and have to start over? My plan is to mount it, see where it indexes and mill the cutouts at 120 degrees with the O.D. directly in the sight plane left intact.

dont take my word for it, but yes, half with 28tpi is the standard ar threads. i am very sure of my answer, but id triple check just to be sure.

Yes,1/2 X 28 RH is correct.

Thanks for the cofirmation

1911 guy, you might be interested in this (http://www.homegunsmith.com/cgi-bin/ib3/ikonboard.cgi)

There are a lot of interesting gun modifications as well as scratch built guns done by professional machinists and amateurs alike.

-Nick