What could have been: The RAS-12 semi-auto shotgun

[BlackIce_GTS]

I remember reading that Firearm Blog article, I was pretty excited until it said it took proprietary ammo. It looks like a lot of people agree with me, based on the comments.
It seems like this sort of thing has failed several times, and for the same reason. None of them are 'better enough' to be able to push their new ammo on the market.
What does the ammo do? It does what 12ga does.
What does the gun do? It does what a Saiga does, but slightly better.
Speaking this thing vs. Saigas, wasn't the Russian importation ban only this year though?

Tangent: what is it about 54R and .303 that makes them work in a double stack when other rimmed cartridges don't?