I have owned a couple rifles with them. Both were .338 win mags and they do exactly what they claim to do. Basically it made full power loads out of a .338 feel like an 06. That's the good part. The negative is that unless you are prepared to wear hearing protection while out in the field as well as everybody around you then everytime you touch one off you are causing permanent cumulative and irreversable damage. It took me too long to convince me of this but I finally clued in. My buddy now has hearing aids in both ears yet he stil shoots a 300 mag with brake on. Hey do what you want, you can even smoke a cigarette while you shoot but realize that you are doing damage.