Re: Civilian/Semi-auto MP5
If I remember right, the civi MP5 model clone goes by "MP5-K" and that is your basic model. Although there are probably other civi varients on the market since the cool thing now is to have rail mounts, reflexive reticles, lasers, lights, ghetto-grips, and a can opener on the weapon.
I think the federal law is no rifle/smg barrels under 16.5 inches. Certain states and cities might have a higher standard...but most don't and you can verify by checking their administrative websites.
The civi MP5 that H&K makes for import to the US is a pretty close copy. The main differences are the longer barrel, semi only selector, and the bolt most likely has a section "milled" out so that if anyone tried to convert the selector mechanism to "select fire" the bolt won't have the surface area to trip the modified pieces on auto fire. Basically even if you made/found a select fire lower reciever, you have to come up with a matching bolt too, which is much more difficult. Also, now you can probably buy the gun new with the collapsable stock or install one without worry of being a felon.
The gun shop I go to down here in Texas has the H&K carbines hanging right up next to the Rugers and stuff, so that leads me to think that if you look around town you will find one where you are. If not, choose a gun dealer at any reputable store and ask them to order you one. The dealer fee is 5 or 10%, or maybe a flat fee like $25, on top of the manufacter sale price. Or if you want to get the best deal, pay below MSRP, look for wholesalers advertising in Shotgun News, make arrangments with a dealer to recieve the weapon (for his fee) and buy directly through their warehouse. (You probably know that guns must be shipped to dealers, never to your door; the only exception in most states being muzzle loaders.) And then there are gunshows. Odds are one will have your gun and possibly at a good price. If not, you can certainly meet dealers who can get you a deal later.
Never say die!
"A nation who forgets its defenders is soon forgotten itself."
"A good shot must necessarily be a good man since the essence of good marksmanship is self-control and self-control is the essential quality of a good man." – Theodore Roosevelt