I don't think "pay enormous cost for a 20 year old firearm, get permission from the local law enforcement (which won't be granted to anyone in California who isn't a Hollywood producer), wait for the federal paper work for several months, pay additional fees" is "perfectly".

Even prior to 1986 FOPA amendment, the number of people who actually owned such firearms was low -- but then again, they were only used in two crimes, in both cases by police officers. Most people who take advantage of this are collectors and movie makers.

As for me, I'll pass on jumping through enormous hoops only to buy a machine that turns money into noise: ask a member of the US armed forces how many times he's actually used the M4 or M16 in fully auto or even burst as opposed to semi-auto. This is reflected in the M16/AR-15 design: they aren't designed for "spray and pray", they're designed for carefully aimed and disciplined fire in semi-auto mode (with occasional full-auto bursts for supressive fire or against metal armour).

> I personally think not. Is there really a difference between hand grenades and automatic rifles? Again, I personally think not.

Well for starters, go to a range that rents automatics (like one in Las Vegas), shoot a fully automatic rifle, and then put it down. Then, pull the pin on a hand-grenade, drop the hand-grenade next you, and then stand in place :-) [No, I don't actually encourage you to do this]. Or you may want to consider why police cruisers have rifles (albeit semi-automatics) but not (explosive) grenades -- rifles are person-to-person weapons, grenades are effectively area/anti-materiel weapons. (Random note: When I lived in USSR, my school PE classes actually included "grenade toss" -- you'd toss a stick grenade filled with inert substance -- as a sport; it's quite challenging.)

I think the difference is immense, they're completely different kinds of weapons -- first of all hand grenades, aren't technically arms if you use the definition of arms used when the constitution was written.

They would not be protected by the second amendment even if fully automatic weapons were. Fully automatic weapons on the other hand aren't protected for the same reason "shouting fire in a crowded theater" (as much as I hate this phrase...) isn't protected, grenades are not protected for the same reason that setting fire to a theater isn't protected.

While this isn't tested, semi-auto rifles, are almost certainly protected -- as they're owned by civilians in great numbers (unlike hand grenades or automatic rifles) and compare to pistols (demonstrated per case law to be protected by second amendment) are far less frequently used in homicides (despite there being more rifles/shotguns in circulation than pistols). This certainly passes the "unusual and dangerous test" used in Heller to rule out automatic rifles, hand-grenades, missiles, nukes, etc... and all the other frequently asserted strawmen.

I'll point you at an excellent book that offers a far more nuanced reading of the second amendment than either side wants to admit -- http://www.amazon.com/Gunfight-Battle-Over-Right-America/dp/... -- including the discussion of what militia means (which is different from what it means in Switzerland, although not entirely unrelated)