I'm no expert, but if you've got a question about this one, I'm willing to attempt an edumucated answer as it relates to my rifle/results.
I've had best luck with Federal Match Large Rifle Magnum primers and the LRM from CCI. Best powder has been IMR4350. I've tried IMR4064, IMR4895 and H4831 to lesser extent. Tempted to try some MRP, but I'm happy with the 4350 and sticking with it.
I do not seat the bullets to spec. The Hornady 190bt has a canelure to crimp in, but that canelure is more than 3/16" out of the case neck when all is said and done. With whatever bullet I'm using, there's at least one bullet diameter seated in the neck. Most ogives provide me with .015" set back from the barrel lands. Seems to be optimum in my rifle. Having your chamber slugged will provide you with a lot of information of where to start. As with any magnum load, start at the bottom of the loading chart, not below, but never more than mid way. Don't be surprised at inaccurate loads. Bullets that work great in my 30-06, aren't optimum in my 30-338. Once an accurate loading is found for your rifle, then experament with loads for velocity/accuracy. All the tricks are in your reloading manuals. But of the printed versions, I think the only one that lists the 30-338 separate from the .308 Norma is the Seirra rifle binder. Powder charges for both are not identical.
Once the brass is fireformed, I only neck size. I fireform with Nosler seconds from my local store. They're cheap and at that point, I'm not concerned if they even hit paper. Case length for me is trimmed to 2.505". That's a little long by spec in the book, but functions well. I do not ream the case necks for uniformity, although I'd suppose that might lead to some better accuracy.
I can digitally photo cases from start to finish if you need it.
There's not much that can walk away from this medium magnum in North America. The previous owner of my rifle had taken more than one Moose with it. One shot kills from well placed bullets. He took a Coyote at ~300yds in front of my eyes the morning I bought it. I have taken several deer with my rifle. One of these days I'll take another Bear and maybe Elk. Bigger animals it was designed for.
-Steve