What is the size of the barrel under the hand guards at the smallest point?
I’m not sure of Colts spec on the diameter but when I have a HBAR turned down in the middle I have it turned to .625" or .650" depending on how hard and fast this barrel will be shot when used.
Thank you!
Forward of the chamber, the .gov profile is 0.670" tapering down to 0.600" before it steps back up just behind the front sight base.
Measuring actual barrels, you will find this dimension runs between 0.590" and 0.605" or so.