The British government is offering to buy Kalashnikov assault rifles and other high-powered guns that become illegal Wednesday under a new firearms law.

Owners have until April 30 to apply for the $265 payment, Home Secretary Douglas Hurd said Tuesday.Under the new law, the penalty for possessing a prohibited weapon is up to five years in jail or a $3,500 fine.

The Firearms (Amendment) Act was introduced after Michael Ryan killed 16 people as he strolled through the small town of Hungerford in August 1987 before taking his own life. It bans the private use of high-powered self-loading rifles like the Kalashnikov, which Ryan used in the massacre, and other weapons including short-barreled, smooth-bore guns.