AR-10 Gas Port-- diameter/distance to breech

[UNCLEDOUGIE]

Hi guys--I'm trying to get the distance from the center of the gas port to the breach face on an AR-10 barrel, and also the actual diameter of the gas port hole. I am putting a new barrel on a French MAS 49/56 and chambering to .308 Win, so duplicating these dimensions is logical. The MAS 49/56 is also a direct impingement system, like the AR-10.

Anybody out there know the answers?

Thanks a million!

[wjkuleck]

What gas tube will you be using?

Regards,

Walt