Yes, with lots of experimentation
Cast bullets can be quite effective on game. I've shot about 140 Lb deer with cast .30-'06 witha muzzle velocity of 2200 fps. It takes a really smooth barrel, a bullet that is compatible with and fits the barrel throat and grooves, and in my case a hard cast bullet designed for and wearing a gas check, and a lot of experimentation. Not all bullet lubes will do it. The technology I use does not result in much expansion, so there is a great need to place the bullet accurately so as to put a hole through vitals.
There is another technology, that of paper patched bullets, that uses really soft bullets, which will result in expansion and will give velocities well above 2400 fps. I have read about, but have no experience with this technology.
Either of these take a lot of work and experimentation. The loading tooling is a bit different, with the neck of the case having to be belled prior to bullet insertion. Casting bullets also is a good bit of work, with lots of tooling, or you can buy them from numerous vendors, some of which will cast to your order and specs. Regardless whether you go cast & lubed or paper patched, you will need to know the throat diameter and shape, rifling design and groove/land diameters.
The powders typically used are either pistol/shotgun powders, but some use of fast rifle to medium speed rifle powders is done. With the pistol powders, there is some danger of double charging. If you are trying for normal .303 or 8x57 performance, you will want to try the fast rifle through medium rifle speed powders, eg 4198 through about 4895. There is a danger with slow powders such as 4831 in reduced loads, so stay away.
The website to discuss this on is Cast Boolits:
http://castboolits.gunloads.com/
