Mitigating flash is my highest priority. My setup is a 11.5" KAC SR-15, and I'm using a Surefire SOCOM556 RC2 suppressor w/ a Surefire Muzzle Brake. This will be a dedicated suppressor, and will never leave the rifle. Saying this, I want to make sure I'm choosing the best muzzle device to use with this suppressor for flash mitigation. I have not seen any discussion on whether or not a flash hider or muzzle brake is better for flash mitigation, when used in conjuction with a suppressor. I've heard that sound suppression can be better and I've heard that it can be worse, so who knows. Pew science has not done any flash mitigation tests as it relates to Surefure muzzle brakes vs flash hiders when used with the RC2 suppressor. I've searched YouTube and found nothing helpful either. Anybody have any real world experience with using both muzzle brakes and flash hiders with suppressors that can speak to the flash mitigation or lack thereof when using brakes with suppressors? I've got the muzzle brake already so it would be the most convenient to use, but I'm wanting to make sure I'm getting the best possible flash mitigation with my setup. Muzzle brake or flash hider w/ RC2 on an 11.5" rifle?

I have a number of yhm fh and brakes on 7.5 to 22 inch guns and there is no difference in flash from fh to brake with the cans mounted.

With barrel lengths ranging from 10.3-14.5" I've noticed no difference between brakes or flash hiders once the can goes on. This is true for my RC2 and Turbo.

I'm not doing any testing that is remotely controlled or scientific so weigh this appropriately. But imo it's a wash.

Flash hiders need to be in open atmosphere to work.  Flash hiders inside a can have NO affect on the flash signature coming out of the suppressor's exit aperture.  The only things that will mitigate flash when suppressed are the suppressor's internal features and the front cap.

If 100% suppressed, id go brake. brake will redirect gasses towards the sides more than a FH. You likely won't notice a difference though.

I think your more important flash mitigator will be ammo selection more than the FH/MB choice. M193 and clones will be flashy, but your ammo designed for SBRs or self defense will have lower flash powder.

I don't think there is a general answer to that question, it depends on each combination

Anecdotal evidence: Omega 9k on a 300blk. Changed from direct thread to plan B + LOM Baby Bell muzzle device. Went from normal "tear drop" muzzle flash to massive, fire-breathing dragon