Shotgun gauges?
 

I'm going to buy my first shotgun but not sure want gauge I should get its for home protection and for outdoors assault.

Most get a 12. A 20 is perfectly capable of doing the job for home protection. I have a 12 as a dedicated defense gun. My wife's 20 ga. 870 express youth model is the back up. I have slugs and buckshot for both of them. If you are small in size a 20 makes particularly good sense. A lot less recoil and weight of the gun and ammo to contend with.

Oh, I forgot to ask, what are you going to assault?

Lol I'm 210 6'1 and I'm mean if I want to get hunting and/or long range firing

Here's a good article...

http://www.backwoodshome.com/articles2/ayoob120.html

Be careful. Most places assault is against the law.

Yea I'm not a crazy person haha just want to be ready for anything

What wrong with being crazy :D

Not a thing haha

For deer a 20 will do just fine. Can get the lower flying sucks and geese too. A 12 to me is a little over kill on a deer. Does awesome for turkey, and if you get one that accepts 3.5 you can hit birds flying high. 12. Ga to me is more versatile than a 20. if you stray away from the two gauges. Shells start getting pricey. I.e. 410, 16, 10.

Yeah, I hate those lower flying sucks!!! :D