Not a dumb question. But the reason that metal patches became as popular as they are these days is because typical cast lead alloy bullets, and even paper patched bullets, are not well suited to the higher velocities that can be obtained with smokeless powder, centerfire, rifles. If you are willing to use your bullets in a 30-30 or similar pressure, similar velocity, loading for your rifle, and you tend to use heavier slugs, you can have a great time.
The effort to cast from a harder alloy such as linotype, or water quenched antimony/tin/lead alloys and installing a gas check and all that is significantly greater than casting for typical pistol loads.
If you trot on down to your local lending library and read up on the subject, you will probably be able to answer your own questions very quickly. As a primer I like the Lyman Cast bullet handbook. There are other volumes on the subject, one published a few years back by Rifle magazine if I recall correctly.
