That has been my assumption up until now. It only occurred to me when I considered my ranging in comparing the ARCO and the ERCO to be down to calibre. I original thought that the ARCO was calibrated for the 6.5 katiba but seems to be for the 7.65 guns. You are right that my low aim was because I was testing for the SPAR 17 not the SPAR 16, my error, as I thought with the SPAR 16 that level of precision isn't required in the optic as the gun cannot manage it. I just meant for clarification.

When I compared it with the ARCO the aim point also seemed LOW, as well as to the left, of point of impact. As an after though could adding a point to the descriptions in game, to clarify which calibre each optic is calibrated for (if they are), be considered. As the trajectories seem to vary with calibre (as they should :)).

Found the issue. It can be recreated by setting "change gunner weapon" and "change weapon" to the same key. this appears to be a bug as it only effects certain things such as the pawnee and some small arms.

I have the same issue. no known steps to reproduce as I can't prevent it. its always like that, but doesn't apply to the hellcat or gunships. I have no mods installed, but also have an issue with fire select on personal weapons see #0017613

Found the issue. It can be recreated by setting "change gunner weapon" and "change weapon" to the same key. this appears to be a bug as it only effects certain things such as the pawnee and some small arms.