What Archer wrote is pertinent as is; Who here has done any blacksmithing school ?
Where they teach, draw square then hammer to octagon & on down till round & the reasons for doing so.
And all this because still some think that because the mandrill is round & the scelp flat that the hammering will also be round.
The drawing out of the metal is faster & therefore more energy efficient in arm movement & forge fuel. The taper is more controllable as is the straightness of the work piece.
To hammer round all the way is a botch & very difficult to do. Try it.
As stated by another poster earlier, even the big hammer forging barrel machines do it this way.
This stuff appears to not be understood or well known.
If a person has the practical experience then they know.
O.