heavy barrel versus normal

[tmckay2]

i have a heavy barrel 20" rifle. im looking at replacing the front sight with a low profile gas block and flip up sight. does anyone know what the diameter of the gas block id need with a heavy barrel? i see .625 and .75 listed the most

* edit: nevermind, i found it, says standard and heavy are the same, lightweight and bull are different

[Circuits]

Most will be .750", to take advantage of standardized parts available in that dimension. To be certain, use calipers to measure the barrel diameter immediately in front of the FSB, and that should represent what you need. If it's not .750, you'll need to look for an "unfitted" gas block that can be reamed to the diameter you do need.