Are you in the US? I didn't thing silencers were legal.
Silencers / Suppressors / Cans are legal in the U.S. in most states. Certainly here in PA.
There are requirements to be fulfilled.
If your local police force cooperates they can approve you for a suppressor after a backround check. If not you can have a NFA Trust drawn up by an attorney............ or maybe even Quikbooks. Me, I paid $500.00 to an attorney for a NFA Trust. http://www.petryfitz.../NFA_Trust.html
With a trust you do not need the approval of local authorities.
Once the necessary paperwork is completed you apply for approval to the BTF and submit a non refundable $200.00 for the necessary Federal tax stamp. As of this post it takes 6-7 months for approvals.
It does take time and money.
Shamu Is Right...
You Can Own A Fully Automatic Weapon Too If You Get A Class III License.
The thing is, once you get the license, The ATF can Come & Inspect Your Home At Any Time.
So Make Sure your "i's" Are Dotted & "T's" are Crossed otherwise...
JAILTIME BABY!!!!!