I don't load 50BMG so my advice is probably not worth a shit. (I do load some big super magnums though).
My buddy loads 50BMG but he's not that great at it. He cuts a lot of corners and the ammo shoots like crap but I know a couple things having tried a few things on his minimal set up:
1. You need a stout press specifically for 50BMG parent cases. (same for .416 Barrett) it needs to have the 1 1/2" threads. RCBS and Hornady I believe make some single stage presses. The Dillon 4 station .50 BMG press is a turret press specifically for that cartridge. Something that has a huge leverage advantage to reduce strength needed for sizing.
2. Sizing takes a huge effort if using LC brass. Don't use the Lee press because your linkages will break and/or the casting will shatter.
3. Dillon makes a FL carbide sizing die but that die is like 800.00 bucks. Apparently this makes sizing easier, and you will want to F/L size anyway.
4. You will need to trim. Again Dillon makes a press-mounted trimmer that would make this easier.
5. You will probably need to swage the pockets
6. You will want to anneal the necks probably every firing.
7. The 750gr AMAX bullets are probably the better shooting bullets other than some solids that cost 2-3 bucks each.
8. You can use Hodgdon US869 for powder and is readily available/cheap. Buy in 8lb jugs. Vihtavuori makes a great .50 BMG powder as well. Forgot the name 2N29 or something.
The handloading of .50 BMG takes a huge commitment, as none of your existing equipment will work. If you're committed to it, then you already know this.