Folks, I spoke with H&R and they advised that Marlin is making this barrel blank for them with the Marlin current twist which is 1/20. Apparently, the spec. for the 44 mag was copied for the catalog and is incorrect. I also brought up the issue of overbore.
They stated that the bore is.425 +/- .001 and the groove is.431 +/- .001 which is the SAAMI specification. My research shows that SAAMI specs the 44 magum RIFLE barrel with a larger bore and groove than the SAAMI 44 magnum PISTOL probably due to the differences in pressure. Is this what leads people to believe they are overbored?
SAAMI 44mag pistol: Bore .417 +/- .001, Groove .429 +/- .001
SAAMI 44 mag Rifle: Bore .424 +/- .001, Groove .431 +/- .001