Hi Whisper, Gun situation here, still liberal.
You can own as many handguns as you want, but no permit to carry as of this moment, unless you really have a documented death threat. As for long arms, the ONLY long fiream that you can purchase at a "gun store" is a shotgun or .22LR.
AR-15s or more popular here as M16 or ARMALITE,
BABY ARMALITE(for the shortened version!!)and
INFANT(8" or 6" barreled version!!, but it works).Started of as loose(unregistered) firearms, bought from insurgents, awol soldiers, vietnam war vets, smugglers, gun runners etc. then you hold on to this for a while and wait for an "amnesty" offered by the government which allows you to register your M16s, no questions asked, just submit the requirements. Cost is around USD 200.
About the availability of parts. Almost all the parts needed to upgrade your M16 are available here, except for the lower receiver. The barrel is a bit hard to find and can be very expensive around USD 500 for a J&T 16" M4 non chromed barrel!! All other parts are abundant, but expect double in price.
The small parts, like springs, detents, bolt parts etc. I order via the internet usually to be delivered in a U.S. address, then just wait for that friend or relative to bring it home for you!! But the "main parts" like the barrel, stock, receivers(upper or lower) you cannot.You can be in trouble w/ the law by doing so.
So you will just have to bite the bullet and pay for the price if you really need it(if you can find one in stock) here are sample prices of parts here in USD.
CAR-15 6 position telestock USD 200
J&T 16" barrel non chrome lined USD 500
DPMS or BUSHMASTER M16A2 upper assy. USD 310
Selling prices of beaten up M16 is around USD 650. The nice shapes goes for around USD 1000.
That is why most of the M16s here uses old lowers made by COLT(mostly vietnam vintage) or by ELISCO(mfg under license from COLT during 1980-86, for use by the Armed forces).
The way to go here is to look for an old ELISCO or COLT then cut the barrel to your desired lenght if you dont like the 20", the next length is 13.5", get a new telestock or upper, some internal lower receiver parts and I guess you are ready to go!!
You can now find BUSHMASTER M4 in the police use and some M16A2 in the Military, but the old M16A1 is still very much in service here.Regards