Thinking outside the box - can the magnets be set up in a rotating order to impart a spin? If the projo is a bi-metal layering of ferrous/non ferrous material, so it rotates to the new magnetic 'grip"?
I'm afraid not, I was thinking the same way originally. When the coils generate the magnetic pulse down the barrel, it's a field that propagates evenly (remember the Right Hand Rule for magnetic field?) when the current travels down the coils. You *could* set it up so the pulse follows separate coils wound into a rifling shape to impart a spin, but since the projectile isn't directly in the epicenter of the magnetic field, there will be a dramatic loss in velocity.
Personally, after seeing his solenoid-esque feeding system, I would set up the "bolt carrier" itself impart a spin on the projectile just as it is tucked into the barrel and trips the IR sensor. On a simpler scale, imagine having a power drill with a very light grip on the bullet, spinning it at full RPM, then a little linear actuator giving it a little poke on the tail of the bullet to push it out of the jaws and into the IR field, starting the sequence and flinging it down the super-smooth Teflon barrel. Eh? Do you think that would be an effective starting point? Granted it would slow the full-auto sequence way down as well as total lock time, but it would allow you to make good, well placed shots... Just thinking out loud.
Regardless, this is still very impressive after him building the thing in his college apartment with hand tools. I'm really from the same crowd as him, and I would love to have a go at one, building off of his design (as he wants everyone to do). Plus, I'm no longer on a college budget
. I'll happily buy coils that are more than $15 apiece