One thing I’d recommend is measure the overall length (OAL) of your factory ammo and record it box to box.
There are brands of ammo that have significant variances with seating depth and some rifles are very sensitive to this. The key would be to figure out what OAL produces the best groups.
But this is just one factor and the whole advantage to handloading ammo is that you can control many of the variables. The ability to load to a specific OAL, at a specific powder type/charge, etc, etc is what makes handloading worthwhile.
One note about getting started in handloading. I think many guys look at all the toys/bells/whistles and assume that it takes thousands to start handloading. The reality is that the RCBS kits out there for $300 really do contain almost everything you need to get started except bullets, primers, and powder. There are a few things like a micrometer that you also need, but overall the entry price is pretty low.
I load thousands of rounds per year using a RCBS JR3 press that I bought for $20. This replaced an old press that used dies that are no longer available. Until i got a digital scale, I used a powder scale my dad bought in 1965 and I still use the powder measure he got back then. I prime using the press with an auto-prime feed option I got on eBay for $30.
Just to say if you’re thinking about getting into the game, don’t overestimate the budget and whatever you do, do NOT be convinced you need to “go big” with a top of the line progressive press.
Grouse