O'k I checked gas port size and it seems to be the same as 30-06 barrel .078, I used a 5/64" drill bit and it fit both barrels the same.My barrel is a nos SA dated 9/65. I drilled the barrel with a 3/32" bit which is .0938. Test fired the rifle and the ejection is better. Now ejects about 5 o'clock and doesn't hit my forehead. Now the question is ,should I go a little bigger and try to get it to eject to at least 2 or 3 o'clock.