Based on everything you’ve said so far:
- Brass: You specifically mentioned FC brass. I rarely have issues with brass, but when I do it’s FC. Going with Alpha/Lapua is never a bad idea, and if you have the appropriate firing pin go with small primer brass.
- Dies: As mentioned, you don’t need one of the trendy overpriced die sets. Forster and Redding dies are just as good as anything else. I typically prefer the Forster micrometer seater die over every other seating die out there anyway. Also, if you aren’t already using a mandrel to set neck tension, try that first. I highly recommend a carbide mandrel too (one place worth spending extra money in my opinion).
- Trimmer: Definitely not a necessity, but being able to trim, chamfer, and deburr all at once and in 3sec is so nice. I went with the Giraud about 2 years ago and haven’t looked back.
- Annealing: I’m not 100% convinced it’s necessary for precision/low SDS, but have been doing it in some fashion since building my first rifle. Started with a drill and a torch, looking for the glow in a dark garage, and now have access to an AMP at my club. But for reference I’ve had SDs ~5fps using the drill/torch combo.
All that to say, I’d start with more premium brass. That and going to Varget (more temp stable than 4064 anyway) should reduce your SDs by a statistically relevant amount. The rest will just make reloading easier/faster, not necessarily more precise rounds.