Anyone have the dimensions - diameters - of the African or PH barrels?

Looking to have a customer 416 Remington barrel made and I have a standard Extreme stock that takes standard barrels. Now, assuming you need .120" - .125" wall thickness, that puts the required end diameter at .656 to .666. The standard barrel is .666. However, looks like I could easily go .040 over and still fit with rooms left over.

Thoughts? Measurements of someone's barrel?

Thanks!

Eric