Washington State recently "fixed" the regulations concerning handguns and hunting so that it is now legal to carry a handgun for protection even when archery / muzzleloader hunting. (With suitable prohibitions against using the handgun for dispatching wounded game or for hunting...)
However, there is still the presumption of wrongdoing if you have a rifle in the woods during elk or deer modern firearm seasons and don't have the appropriate tag.
It is legal to hunt forest grouse with a rifle in Washington State. (Maybe not the wisest choice, but legal.)
So, hypothetically speaking, I could have a hunting license & deer tag and be out during elk season looking for grouse. Good practice for next year, using my deer rifle. However, this is a game violation unless I have an elk tag.
The presumption of guilt because you don't have the "correct" rifle isn't limited to worried tourists and EBR's, in other words.
In an ideal world, the mere possession of any weapon should not be a crime. If it is used in an illegal manner, proper penalties should exist, of course.
Since it isn't an ideal world, there is quite a bit of "possession = intent" thinking going on out there. Even though it is wrong, it is unlikely that that type of thinking will go away, IMO.
(By the way, I know of at least one game officer who now knows about Winchester 9410 shotguns as grouse guns. "Yes, I know it looks like a .30-30, but it's a shotgun. Honest officer, why would I make this up?")