I am probably the wrong person to respond, since I am primarily a deer/elk hunter simply looking to "stretch" my effective range. I have 3 rifles, of which only 1 has anything that it didn't come from the factory with. All three shoot sub-moa to 600-800 yards, but not necessarily 1/2 minute.
I mention this because what your "goal" is might help with the answer. For example, since I live in Idaho and hunt in some insane mountains, carrying a 12lb gun at 46 years of age is not that appealing to me.
So, are you mostly looking to learn to shoot or hunt long range? If your a hunter, will you be carrying the gun a lot and is weight likely an issue? If you hunt will you be hunting only deer, or will elk and other large game(bear, moose, etc) part of your plan? Do you reload or do you plan to? How recoil sensitive are you, you mentioned .30's and bigger, so I hope not much.
Here is some of the advice you are likely to hear:
If you plan to hunt, particularly anything larger than deer, at distances that exceed say 800 yards, then yes a .30 or a .338 would be a better choice, though since I am a die hard 7mm man I would argue that isn't the case.
I was a die hard anti-brake guy until I got my first gun with a brake and not I am a die hard brake fan. 2 reasons. First, the recoil reduction is very helpful for range time. Second, spotting shots at long distance is extremely helpful. But never forget your hearing protection.
Don't go get a big fast .30 or .338(or maybe 7mm) and put it on a 22" or 24" barrel, you just loose too much speed and negate the benefit it brings.
I know you asked about guns not all this other stuff, but this is what will help you make your decision.
Once you pick a caliber to fit what your needs are, you will decide on a factory available one or a Wildcat.
For factory calibers I would look for first tier options to include Savage, Tikka, Howa/Weatherby Vanguard, and Remington. I think the concensus is the first 3 are good values and all have reputation to shoot out of the box. Remington is simply the easiest to semi or full custom, followed by Savage. Savage also chambers a number of models is 6.5x284, a good LR option.
I think for about $1200-$1500 you could pick up a fairly LR ready Savage, add good Talley rings, and a Vortex HS series scope and be ready to go shoot as far as someone with your experience can realistically handle and expect with no more than a little experimenting with different factory loads or reloads to be sub moa.
You can make an argument for many manufacurers, for example I have and love my Sako, but I would start with the 4 above for simplicity.
For realistic 1/2 moa, especially at long distance or with minimal load development, you will need to look into custom barrel, stock, trigger, and likely an accurized action at about $2500 bucks. You will likely need a few months to a year to be able to get it all done. I think if you find this will be a true passion you will have wished you started here, with the best.
