Sounds like you need to do a little reading by your post. To which Remington mag do you refer? The .30 Ultra mag? If so yes the bullets interchange as they are both .30 cal or .308 diameter. The Ultra mag is more powerful. Most .30 cal bullets do not exceed 220 grs. Having said that, there are much better choices for hunting lion, though properly hit with a good bullet a .30 mag is adequate. I would personally prefer at least a .338 Win mag with 250 gr bullets or even a .375 H&H as minimum but your time is running short so if you plan to use a .30 mag, get some good advice on bullets and get in lots of practice. Good lion bullets are Nosler Partitions, Swifts, Barnes TripleShoks, and there are many more, but it must be a quality soft nose, no solids. Lion are tough and dangerous animals and not to be taken lightly. The .375 H&H is the legal minimum in some countries, not sure about RSA. Also this is not the place for that 4-20X scope. Use a lower power variable, no more than 3-10X and keep it on lower settings unless you need the extra power for a longer shot. Good luck, hope you get one.
