IGB Austria online
Well here is another carbine idea. 9mm, 40 S&W, .357 Sig., & 45 ACP. I noticed them in the 2009 Lone Wolf catalog. I think the idea is you might add on a few other items (like Mako Security).
I'm always looking for a .357 Sig carbine (doubt I'll ever buy one). In the end, it appears the advantages of having a common caliber in a carbine like the Kel Tec sub-2000 or Mech Tech CCU are outweighed by the round's limitations. The long barrel only offers minor improvements and it would be far easier and more effective to just pick up a .223 AR-15.
I'm not sure what to think about these 16" barrels. I don't think it does it for me. I would go for the sub-2000 or CCU first. It is minimalistic, and while light and easy to carry is nice, if I'm going to carry around a rifle, I would want a little bulk.