The Firearm Blog has a three-part guide on how to buy suppressors. It is a good write-up
Part 1: http://www.thefirearmblog.com/blog/2016/03/24/beginners-guide-suppressors-part-1/
Part 2: http://www.thefirearmblog.com/blog/2016/03/29/a-beginners-guide-to-suppressors-part-2/
Part 3: http://www.thefirearmblog.com/blog/2016/04/04/beginners-guide-suppressors-part-3/
From: The Firearm Blog
