Here is the statute law for the state of California regarding various weapons:
2007 Dangerous Weapons Control Law 12020 thru 12040 Unlawful Carrying and Possession
ARTICLE 2. UNLAWFUL CARRYING AND POSSESSION OF WEAPONS 12020. (a) Any person in this state who does any of the following is punishable by imprisonment in a county jail not exceeding one year or in the state prison: (1) Manufactures or causes to be manufactured, imports into the state, keeps for sale, or offers or exposes for sale, or who gives, lends, or possesses any cane gun or wallet gun, any undetectable firearm, any firearm which is not immediately recognizable as a firearm, any camouflaging firearm container, any ammunition which contains or consists of any flechette dart, any bullet containing or carrying an explosive agent, any ballistic knife, any multiburst trigger activator, any nunchaku, any short-barreled shotgun, any short-barreled rifle, any metal knuckles, any belt buckle knife, any leaded cane, any zip gun, any shuriken, any unconventional pistol, any lipstick case knife, any cane sword, any shobi-zue, any air gauge knife, any writing pen knife, any metal military practice handgrenade or metal replica handgrenade, or any instrument or weapon of the kind commonly known as a blackjack, slungshot, billy, sandclub, sap, or sandbag.
Several other states have similar laws. <archer>Fortunately, after fifteen years of boarding school locker room fights, I’m an AWESOME shot with a wet towel. I am a “zone” of “danger” at the pool. Get it? Get it? Oh, I’m sorry, I can’t hear you OVER THE SOUND OF MY OWN AWESOMENESS!</archer>
With regard to “powerful new weapons”, you’ll either have the BATFE at your door demanding to collect taxes and examine your records and approvals per the previously referenced 27 CFR 479, subparts D, E, F, G, I, K, N, and O, the Department of Justice climbing up your asshole looking for Internatinoal Trafficing in Arms violations (pretty much anything you do including nothing at all will violate some ITAR restriction), or Samuel L. Jackson showing up at your door ‘inviting’ you to join ‘the Avengers Initiative’ which will consisted of a bunch of overprivliged child-men and one woman who would just as soon interrogate you and throw you off a ledge as to have coffee with you.
So…maybe just stick with your “Angry Birds”-killer iPhone app.