That plot is what I expected to see. I think the software has changed a little since my older RS232 port version of the instrument was made.
The scope looks snazzy, but for such a short range, I think I'd probably use a laser bore sighter. Green ones visible in daytime are as low as
$20 now on Amazon. That one claims to be adjustable for windage and elevation (centering). You could set it up to be right on, though you'd probably need a "top" registration mark painted onto it.
Nice setup, though. Not too many folks have their own version of a universal receiver.