First of all, welcome to Washington.
Pomeroy is in the middle of nowhere, and that’s the best part of Washington. Most of the population here is between Olympia and Everett along Interstate 5. It's crowded, and we have to leave to hunt. Most westside hunters are knuckleheads, and luckily for you, most of them aren’t willing to drive as far as Pomeroy to hunt. Westsiders also don’t have time to scout, so we go all the most obvious places. The locals know the good spots, so they have better luck than we do. Again, as a local, you’re looking good. Get to know the folks in town, keep your ears open, and you’ll soon know where the good spots are.
As of right now, your 12-gauge is legal for everything here, including deer, bear and elk. The country around Pomeroy is flat and open, so a 270 or 30/06 would be better, but a 12-gauge slug will work. WA regs can be confusing. Every three years, the Washington Department of Fish and Wildlife reviews them and moves Game Management Unit (GMU) boundaries, changes hunts, and changes the types of firearms you can use in some areas. You’ll be fine once you get used to that cycle, but it’s frustrating at first. That said, the WDFW seems to have become more responsive to hunter concerns over the last decade or so. Regs usually come out in April or May.
You have to be half surveyor and half attorney to understand GMU boundaries, but this book can help:
http://www.amazon.com/Washington-Atlas-Gazetteer-Delorme/dp/089933329X/ref=cm_cr_pr_product_top/183-3893291-0558607 You can buy it at lots of sporting goods stores here.
Get on out here and spend the summer scouting. Grouse season will be open before you know it, and once you get a deer or an elk in your freezer, you can live off of game.
Let me know if you have any questions.
Okie John