Since the thread has been derailed already I will put in my two cents. Eagle you can attempt anything you wish. Just so you know for research purposes the ATF has a link to all "Rulings":
http://www.atf.gov/regulations-rulings/rulings/index.html
Their are actually three rulings that deal with your proposed setup and why people basically state that open bolt semi's are illegal.
82-2 – KG-9 Pistol as NFA Weapon
82-8 – SM10, SM11A Pistols and SAC Carbines as NFA Weapons
83-5 – STEN MK II as NFA Weapon
Before you get your panties wadded up and start calling me a "Constitution Killer" and make claims that people like me are pro ATF etc. I would like you to realize some things. Going to a gun board and picking fights about the legalities of something is ignorant. Take it as said that people who frequent gun boards are pro-second amendment. They may not be able to articulate something precisely but, many have a great deal of experience and are well read concerning the law. ATF rulings have been challenged and for the overwhelming majority of them they are found legal and Constitutional. You can hate the ATF all you want but, that fact remain the same. If people would not take up Bower's cause over something as small as the Akins accelerator do you really think anyone will take up your cause? Especially as you are belligerent and agressive to the only people on the planet that would even be partially inclined to take up your cause. Bower's was and is a very nice guy who got shafted by a "letter writer" who could not possibly stand someone doing something he thought was against ATF rulings.
So, please read the rulings and instead of looking to squirm and worm your way around them try to actually understand them so that you can make reasonable decisions. You don't have to like them or agree with them but, try and see the logic to them. That will get you much farther along in your proposed design than picking fights on this or any other gun forum. I can assure you that anything you design for an open bolt semi will be picked apart by gun owners and many a letter will be written to the ATF asking questions. You must have things air tight and sewed up solid to withstand that scrutiny.