Sometimes they do, sometimes not. I have several rifles that I have tried them and was a wasted time. My Savage 112 BVSS-S in .220 LOVES it!!!! Cut its groups from mid .7" groups down to .3" groups with boring regularity. So it cut them in half.

I have put them on our sniper rifles and several field rifles and you will hear that you need to slide them up and down the barrel to find the "sweet spot". From all the ones I have tried, slide it all the way down the barrel to within 3 inches of the forearm tip and start there. If you can not get it to work from there to 1 inch from the forend, it more than likely won't.