You can still purchase fully automatic weapons as long as they were made prior to 1986, with a lot of work done beforehand. This does include the M16.
You can purchase various sniper rifles, even the Barrett rifle.
Semi-automatics, while illegal to do so, with a bit of work can made into fully automatic.
Larger clips and magazines, again what is allowed varies by state, but can be had.
Every state has various laws, but where there's a will there's a way to get basically most things that IMO don't need to be in the hands of your everyday citizen. You want home defense, get a shotgun. I don't believe in conceal and carry, but that's more understandable to me than Semi-automatics. You want to hunt, use a rifle, shotgun, rifle, bow, or crossbow. Semi-automatics here I don't get.
Then you add in body armor of various strengths, Yes....You can get military like weaponry. Guess that's all needed to defend against tyranny though, right?