The perfect gun for you....
O.K. Your needs can only be met with TWO (2) rifle because you want to get into cowboy action shooting. You'd have to get the lever action rifle that the other posters recommended. However, if you have the budget for 2 rifles, then an SKS would be ideal.
Since your range time is limited, getting a terribly accurate sniper rifle would be useless to you as you would not have requisite range time to master wind reading, distance ranging with mil-dot scopes, and bullet drop calculations. A simple gun with iron sights is what you need due to your limited range time. Since you don't want to penetrate armor, my favorite SHTF rifle, the 50 BMG shooters are out. Since you want to use it for hunting, then calibers that are too small are out. You already have a shotgun for hunting small game like ducks and birds. Therefore, you'll want a bigger gun for home defense and hunting large game like deer. Therefore, a AR15 is out as the .223 projectile is too small for deer, unless you like following blood trails for miles. It needs to be easy to use and maintain, so it would have to be a millitary rifle. You want your petite girlfriend to be able to handle it, so it would have to be a gun designed for little Vietnamese fighters. Hey, there's a bit of history to it, too, the Vietnam war. Therefore, you should buy an SKS, Norinco version as they are built for smaller Asian statures. The stocks are smaller and lighter than the Russian and Eastern european AK's. The gun has a chrome lined barrel and will outlast you. It is a great little, inexpensive semi-auto rifle. Enjoy!
BTW, don't worry about overpenetration of the 7.62x39 ammo. Just take groin shots and the bullet will hit the ground behind the BG. Bullets will only overpenetrate into your neighbors' home if you shoot straight ahead by going for head or COM shots. A shot to the BG's family jewels will stop drop him fast without the danger of overpenetration because the bullet trajectory is angled at the ground. Since you live in Washington state, the penetration through trees is a good thing for you in a defensive situation. AR15 cannot penetrate trees as good as SKS.
Personally, I think that the best SHTF gun is 50 BMG such as a Barrett or Serbu. I have hunted deer with my 50 bmg and I can tell you that I did not have to follow any blood trails. It just dropped like a puppet with the strings cut suddenly. A BG shot with a 50 BMG will be split in half. However, 50 BMG rifles weigh 22 (serbu) to 3X lbs (Barrett), so your petite girlfriend won't be able to handle it.
Even though I have many guns, my cheapest gun, the SKS is my favorite. Other semi auto rifles with protruding magazines force you to put your head up high in a vulnerable position to fire it. The SKS has a 10 round fixed magazine so you can fire it from a nearly flat prone position, letting you avoid enemy fire. Great little gun. Enjoy!
1. I'm not ex-military or ex-LEO, but grew up shooting rifles and camping
2. I'm likely to get to the rifle range every 3 months or so
3. I'm a fan of history (the romance of the Garand appeals to me)
4. I currently live in the suburbs
5. I don't expect to fight armored opponents with my rifle; the rifle is for pleasure/target shooting but is also my one SHTF rifle (SHTF = for whatever reason, must head out into woods for extended period of time, or use this rifle against intruders for self-defense)
6. Rifle must be easy to use and maintain, and be able to be operated by my girlfriend if need be (she's 5'6", 125lbs).
7. Cowboy action shooting.
P.S. a Norinco SKS can be had for $150 to $300 at current prices, depending on condition.
