Depends on what is considered an assault rifle. I have several from a number of different years.
The first one is an original assault rifle from the 1780's, and would have been used by a militiaman.

The second one is a assault rifle from the 1840's, an 1846 Mississippi rifle to be exact.

The third one is an 1861 Springfield rifled musket with a bayonet. This particular gun is a Bridesburg contract musket.

The fourth assault rifle is an 1871 Springfield with a trowel bayonet. The trowel bayonet saved Gibbon's butt at Big Hole, because they were able to dig in. The Nez Perce were kicking his butt, and his men had to either dig in or get shot up.

My fifth assault rifle is a 1918 Springfield with bayonet.

And my last assault rifle is an M1 Garand, with bayonet. This rifle was use in WWII and Korea, which is my era.
I don't have the AR15, because I'm too old to appreciate that gun. I have nothing against them for you young whipper snappers, but to me they are Mattel toys. Don't give me any flak over that, if you like the AR 15 or any of the others of that style, which I might add that most of the guys at the American Legion Post I belong to they like them, so if you do also, go for it. I'm happy with what I have, and I'm happy for you if you want something different than my preferences. At one time I owned an SKS, but I gave it to my kid. I have a semi auto .22 long rifle, so didn't really have any desire for the SKS, although I found it accurate and enjoyed shooting it, it was about the same as the .22 auto, only the ammo was more expensive.