Do they really make such a difference?
Which manufacturers are offering them?
JSB do "hand" sort (ie some one checks batches and tosses out the obiously deformed ones) some of their pellets. The best pellest, that is pellets that have the same shape and mass are from the same Die, this gives you a uniform (we are only talking quality pellets here) pellet that will perform the same way each time shot to shot. Not many pellets are die sorted because of expense. You can "Die sort" your own pellets by wieght, this will give you as near as the same die.
i used to do that too.........and i'm pretty sure it made a difference......but now i'm just lazy, besides i'm using daystates 4.53's now, and the quality/pellet to pellet consistency is really good. got 10 tins of the stuff, should keep me shooting till next year sometime???? maybe then i will start weighing the pellets again