I recently purchsed one and placed a Bushnell 6X18 Banner scope on it.My cartridges were my reloads with a 55 grain Hornady V-MAX. I zeroed at 25 yards and then to the 100 yard range. Groups were 5". I began to adjust the harmonic dampener backwards with no results. Taking it back to the muzzle,the groups began to close.Whn I got one ragged hole at 100 yards and 2" high, I began to shoot at rocks about 1/2 the size of my fist and hit each shot.I would never have dreamed such a device as the harmonic dampener would work but was quite pleased.