I've got a pile of S- neck dies,S full-length dies,S small base dies competition seaters, collet dies, body dies, small base body dies adnaseum.
Observations:
If you are dealing with a minimum spec chambered and necked target or varmint rifle there are measureable benefits. Measureable on a roll test at least, proveing it on a target is another matter. Proveing that the incremental improvement will get you one more point or game animal is another.
On a more ordinary, sloppy chambered factory rifle it changes a bit. If the neck is sized down more than a few thou, it's probable that the high dollar neck die will produce more runout that a plain vanilla FL die. The micrometer seaters are worthwhile for convenience if nothing else.
Conclusions:
If you are a no compromise guy who started his system by picking the specific premium brass, buying his own reamers and building from there, then the premium bushing dies fits into that program. If your setup in more pedestrian, then pickup an extra-large cuppa self-delusion first.
Personally, I would have been farther ahead spending the money on good barrels and good brass.
