Link: http://www.ruger.com/SR556VTRecall/index.html
If yours look like this,
it is subjected to recall. You can contact Ruger via
Email: recall@ruger.com
Phone: 603-865-3100
Fax: 603-863-6165
and provide name, address, telephone number, best time to call and the serial number of your rifle.
From: Ruger
