Shawnmoore81 623 Posted November 28, 2014 Have 3 uppers I'm working on. .300 whisper 6.8 spc 7.62x39 I have to find brakes for them. Am I wrong guessing the 6.8 and 7.62 will use .308 brakes. The .300 possibly too? Quote Share this post Link to post Share on other sites
Displaced Texan 11,647 Posted November 28, 2014 You are correct, 7.62 brakes are what you want. Quote Share this post Link to post Share on other sites
Shawnmoore81 623 Posted January 17, 2015 For future reference .300 whisper and blackout are the same 6.8 and 7.62x39 use a .308 brake I learned the hard way and will be listing a couple .300 brakes Quote Share this post Link to post Share on other sites