Does the 6.5 Grendel cartridge fired out of a barrel of length greater than or equal to 18" benefit from the addition of a flash suppressor? Or, is there really not much flash to suppress anyway in barrels that long?
Well, I would be doing some night shooting if I had a Grendel upper.
So, you're saying that even from a 20" barrel, the Grendel cartridge will have enough unburnt powder left at the end of the barrel to produce a sizable flash?
I can't comment on flash suppressors, but can tell you a brake does help reduce recoil. I just built a Grendel at 18" and, could really tell the difference between braked and non-braked. Especially if you want to spot for yourself at long range, consider a muzzle brake.
There has been much written about this and actually it's not the unburnt powder that does it but the the gasses hitting the oxygen that causes the "corona" you see.Doesn't matter why, but the effect is enhanced by a shorter barrel and high velocity.Actually you may want to look at Primary weapon's "flash suppressing compensator" they work pretty good at doing both.