I'll solve this whole thing for you right now, I have a self timing Area 419 hellfire 6.5 brake sitting idle, pm me your address, I will ship it to you to try for yourself. Run a test next weekend with and without it on if your Bergara is threaded. Send it back when done, I can't see how a muzzle brake could get damaged.
This is a simple offer.
EDIT: I would expect a slight review on here after though.
Did OP take you up on your offer?