They work. Many 1000 yard Benchrest shooters have been using them for years. They are not magic, but one important part of the whole equation. Long range BR shooters sort their bullets with the Juenke machine, sort by length based on ogive to boattail, and many now re-point the bullets and unform the meplat. These are serious shooters, not plinkers or people loading hunting ammo.
Having said that, I don't know any 100/200 yard BR shooters that use them.
