I own a Norinco Mak 90 Sporter rifle serial no#93,44XXX. I have several questions regarding
Modifications. I have allready added the following US parts, buttstock, pistol grip, lower forearm,
Ultimak upper rail and a Tapco G2 fire control parts. I currently live in Nevada where we do not
have laws against assault rifles, but still would like to be within the law. Please let me know if any
of the below modifications can be performed legally.

1. Would it be legal to install a folding stock. i.e. ACE LTD.

2. Can I legally thread the barrel and install a SmithEnt. Vortex flash hider.

3. If the above mods are legal, what or how many USA parts are needed
   due to law 922r

4. Would I have to have muzzle device permanently installed.
 
So, anyways if anybody can give me any expert advice on having these evil features it would
be greatly appreciated.

Parts that can be replaced with US manufactured ones for compliance:

Receiver
Buttstock
Pistol Grip
Handguards
Hammer
Trigger
Sear
Gas Piston
Barrel
Magazine Floorplate
Magazine Follower

If you are using a stamped receiver and no muzzle device, you need 5 US parts.  With foreign muzzle device, 6 US parts.

Milled receivers only need 4 US parts if you are not using a foreign muzzle device.

You can have no more than 10 foreign parts in the rifle, including trunnions, for it to be considered a US rifle.

If I've missed anything, I'm sure someone will add it.

A domestically produced sporting rifle may have no more than 10 imported parts for it to still be considered domestic. So, depending on whether you have a milled or stamped rifle and whether or not it has a muzzle brake, you will have to replace up to 6 of the imported parts with made in the USA ones.

That's a key phrase there. You can't just slap on some US doohickies and go. You have to replace parts that were on the original rifle with made in the US ones. That's why it works in our favor that the butthole stocks are counted as 2 parts during the parts count for importation. If it were only counted as one part you would be adding another part to the total count when you put a pistol grip on. It could easily be offset by adding a US pistol grip, just like a made in the US muzzle brake will, in effect, offset itself but it would add an additional twist to an already convoluted subject.

Replacement US parts include:

Buttstock 1
pistol grip 1
upper and lower handguards 1
muzzle brake 1
gas piston 1
hammer 1
trigger 1
disconnector 1
magazine body 1
follower 1
floorplate 1
reciever 1

Please note that the upper and lower handguards are counted as one part. If you only replace one or the other it will not be counted as a US part regardless of what is molded into the plastic. Both the upper and lower must be of US manufacture for it to count toward changing it's import status. Also, a muzzle nut is not an attachment if it is secured properly but a brake is an attachment regardless of whether or not there are threads holding it on.

Thanks for the reply, however I am still a little confused. Since I currently have 6 US parts
that include buttstock,pistol grip,upper and lower handguards,Tapco G2 FCG. Would that allow
me to modify my rifle to include a folding stock and flash suppressor? The 922r law only
specifies buttstock and muzzle brakes. However, the stock and flash hider are US manufacture.
Also would it be safe to say that since my rifle will be replaced with a US folding stock, that my
parts count is still above the requirements of 922r and so it would be legal if a flash suppressor
is added because said weapon is of a US manufacture according to 922r.

So the definitive answer is:

Folding stock YES or NO

Flash suppressor YES or NO

Thank you for your reply, as this question I'm sure has been discussed to death.

unless NV has more restrictive laws than fed.

stock YES
threads YES