Here is the "Cliff notes" as I see it.
Cast bullets can be used in the vast majority of pistol rounds successfully without a PHD in casting. The reasons being...they are larger bullets and easier to cast...they are rarely pushed much over 1400 fps....top accuracy is not needed (in fact most people cannot shoot pistols well enough to tell)
Cast bullets in factory rifles gets more challenging. If you stay under 2000 fps and are satisfied with 3 MOA at 100 yards you can get there with some work. If you want to go over 2200 fps and/or get 6" groups at 300 yards it is not a walk in the park. As bullet diameter lessens, the challenge will increase.
I doubt there are more than a dozen people on this site that can achieve 2 MOA at 300 yards with cast bullets at 2500 fps MV. They have shown us how to do it. It is not easy.
Years ago, I started a thread when PC bullets became "the new thing". It asked people to post if they had been able to get 2 MOA at 100 yards with PC'ed bullets. IIRC, after months of activity, there were a handful of folks who had been able to do it.
You need to learn enough to meet your requirements and enough to know if your goals are realistic. If you cannot cast a bullet for the .38 Spl that will hold 3" at 50 yards out of a decent carbine or target pistol, you are not ready to move on to "bigger and better" things.