Mine won't get shot now enough to hurt the rifling with the oversized groove diameter. My brother will use it as a guide rifle (he's 64 now), or late season panic moose rifle if he can't round one up during the calling time with ML or bow.

Mine has .019" headspace on necked up 8x57 brass. The shoulder start is supposed to be the same for both 9.3 and 8mm rounds, so shows my rifle's headspace is .004" worse than your rifle's. I don't see it as a big problem as my rifles all use handloads regardless.