I've mainly used them on 6.5 CMs, but have one on a 30 SM a 6.5-284 right now also. They work - as a brake and a tuner. Not that a 6.5CM needs much of a brake, but shot spotting was easier with it than a suppressor past 500 yards. The tuner is simple to dial in, and it actually changes group shapes. I'll be getting a BR model for my next 1.250 straight barrel. It's a quality part, it's about as effective as other brakes I've used (but I have all those up there for a direct side by side at some point), and it cleans up easily/well.