Will this work?

AR/M4 AR General Discussion
1

I am thinking about a 10.5" barrel with a 10"kmr (the bcm website says actual length is 10.5") with a vortex glass break flash hider. Will the flash hider extend far enough to where the gasses won’t get to the handguard?

2

I don’t know, but BCM sells 11.5 uppers with KMR 10s…they look like this:

3

Don’t have experience with the flash hider but for reference here is a Noveske 10.5 with A2 and a BCM KMR 9", actual length listed 9.4"