View Full Version : ar15 bbl machining

mike in co
07-10-2008, 07:44 PM
well guys i asked on ar15.com and got no answers. most guys ASSEMBLE rifles, not machine them.
i have a book with the basic size/thread info but (for now) i have a few questions.

how is the locating pin in the bbl extension installed ?


how does one time the gas port to hit a groove, and not a land ?

and yes i do shoot br with ar's

mike in co

07-11-2008, 12:22 AM
The pin in the barrel extension is just a drive fit, and it need not enter into the barrel threads, but that's your choice. Timing the gas hole to a groove......almost impossible. I push a lead slug to the spot in the barrel where the hole will be drilled to help eliminate a burr, then push it out. Drill first with a #45 drill then ream with a #43.

07-11-2008, 06:03 AM
I use a borescope with a stop on it to find the location of the gas port. Look for the groove and rotate the barrel in the mill vise till that spot is up. I also use a lead slug to help stop the burr.

07-11-2008, 05:27 PM
Mike I sent you a pm. I have the instructions you need but it would be diffficult for me to post,can I fax to you

mike in co
07-11-2008, 09:05 PM
you have email...