Mtn,
I think it should be pointed out a LOT may depend on gunsight, used too. While none of our aircraft have much in the way of a true HUD, there's a lot more valuable information you can get from the right sight that can help you aim without tracers. Some sights IMO are just better than others. They'll all do the job, but some, especially the simple pipper-only or ring-and-pipper leave you with a lot of guesswork, while others give you a LOT of information.

This is my favorite sight. At a glance you can get your wing attitude and lift vector which gives you a rough estimate of the path of your bullet stream during maneuvers; basic ranging if you know your target's approximate wingspan; and rough lead-computing using the notches above and below the cross (plus ordinance aiming if you REALLY want to get technical with your dive angle, altitude and airspeed during bombing and rocket attacks). I'm not sure what the two angled lines mean, but this seems to match up with the K-14 sight's ground attack mode, so may have an application in ground attack (range finding?). However above the cross there's gaps in the rings at the same angles, so they may work with the vertical and horizontal cross-hair as a rough bank indicator.