...I would think because of th fast powders required by the 44 mag's limited case capacity and the very quick expansion ratio created by a 44 caliber bore diameter, a 16" barrel would be plenty sufficent to extract maximum velocity with suitable powders and maximum loads..A longer barrel would likely serve no useful purpose so far as boosting velocity, and a shorter barrel would run into trouble with federal law on barrel lengths for rifles...This is of course just a surmise, exhaustive testing would have to be preformed for the rock solid data..
