Silencers are illegal under Minnesota law.
You can read the statute below.
2007 Minnesota Statutes
609.66 DANGEROUS WEAPONS.
Subd. 1a. Felony crimes; silencers prohibited; reckless discharge. (a) Except as otherwise
provided in subdivision 1h, whoever does any of the following is guilty of a felony and may be
sentenced as provided in paragraph (b):
(1) sells or has in possession any device designed to silence or muffle the discharge of
a firearm;
Subd. 1h. Silencers; authorized for law enforcement and wildlife control purposes. (a)
Notwithstanding subdivision 1a, paragraph (a), clause (1), licensed peace officers may use devices
designed to silence or muffle the discharge of a firearm for tactical emergency response operations.
Tactical emergency response operations include execution of high risk search and arrest warrants,
incidents of terrorism, hostage rescue, and any other tactical deployments involving high risk
circumstances. The chief law enforcement officer of a law enforcement agency that has the need to
use silencing devices must establish and enforce a written policy governing the use of the devices.
(b) Notwithstanding subdivision 1a, paragraph (a), clause (1), until July 1, 2011, an
enforcement officer, as defined in section 97A.015, subdivision 18, a wildlife area manager,
an employee designated under section 84.0835, or a person acting under contract with the
commissioner of natural resources, at specific times and locations that are authorized by the
commissioner of natural resources may use devices designed to silence or muffle the discharge of
a firearm for wildlife control operations that require stealth. If the commissioner determines that
the use of silencing devices is necessary under this paragraph, the commissioner must:
(1) establish and enforce a written policy governing the use, possession, and transportation
of the devices;
(2) limit the number of the silencing devices maintained by the Department of Natural
Resources to no more than ten; and
(3) keep direct custody and control of the devices when the devices are not specifically
authorized for use.