Has anyone loaded any of the Barnes 250gr bullets in a 9.3x74r double rifle and if so how far off was its requlation.

I wouldn't use that bullet in a double rifle.
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"Serious rifles have two barrels, everything else just burns gunpowder."

It is not advisable to use monolithic bullets in a double rifle. Seems that they do not compress enough as they travel the barrel. This can result in ironing the rifling, and literally imprint the rifling through to the exterior of the barrels, as well as potentially breaking the solder bond between barrels and the rib. Not worth the risk!