I wonder if any of you have used the Time Precision Super Tune device? It is a muzzle weight that has an adjustable collar. By screwing the collar in or out if apparently alters the barrel vibration, thus affecting accuracy. I have used one before. It worked well for me on my 243 Winchester. It had a 1:10 twist premium barrel that was 0.750” in diameter at the muzzle. I decided that I wanted to use the Hornady 87 VMAX and H4350 due to its reported temperature insensitivity. I seated the bullet to just touch the lands and worked up in powder charge to safe maximum. Then I attached the Supertuner and started shooting groups. By the time I got to 4 clicks out I had great accuracy. I did not get better accuracy at any other setting in this particular application. I was able to get sub 0.5 MOA groups out to 500 yards. That is not that great for 1000 yard benchrest competitors but for this varmint hunter it was better than I had ever been able to do prior to its use. I have rebarreled this rifle with a heavier barrel which is 1.0” at the muzzle. I am having some difficulty coming up with a consistently accurate load for it. I am thinking to try another Supertuner (my old one is too small in diameter to work on this fatter barrel). I was just hoping to hear what others have found with this and other devices. I have read that they are very commonly used in 22 rimfire competition but they hardly ever seem to be mentioned for centerfire rifles. Why is that? Thanks for any input, Rufous.