There are several type of Class 3 items that are restricted by the National Firearms Act.
Each state can impose additional restrictions on the sale,
purchase, and transfer of class 3 firearms in addition to the compliance that is required with the National Firearms Act.
In Missouri you can own the following items that are regulated by the the National Firearms Act:
Machine Guns **
Silencers* after 8/28/08 which are a curio, ornament, or as a keepsake if you are a collector.
Short Barreled Shotguns (SBS)
Short Barreled Rifles (SBR)
Any Other Weapon (AOW)
In Missouri you cannot own the following NFA restricted items.
Silencers *- prior to 8/28/08 which are not classified as curio, ornament, or as keepsake, or non-functioning devices
Destructive Devices (DD)
** Must be a curio, ornament, or keepsake, and such person is an importer, manufacturer, dealer, or collector licensed by the Secretary of the Treasury pursuant to the Gun Control Act of 1968, U.S.C., Title 18
* NOTE HB 2034 SECTION 571.020
As a practice matter the item does not have to be a C&R if you are a collector which is usually evidenced by having a C&R license. That is if you have a C&R license you can have a non C&R Silencer, machine gun, SBR, or SBS as a keepsake.
This act allows licensed importers, manufacturers, dealers, or collectors to possess, manufacture, transport, repair, or sell a firearm silencer as a curio, ornament, or keepsake.
Currently, it is not a crime for a person to possess, manufacture,
transport, repair, or sell a firearm silencer if such action was incident to dealing with the silencer as a curio, ornament, or keepsake, or it is used in a lawful dramatic performance, but only if the silencer is in a non functioning condition. Under this act, the silencer would not have to be in such non functioning condition.
This section is identical to certain provisions to SCS/SB 1172 (2008).
Follow this link to find out more about Missouri and NFA restrictions on Class 3 Firearms