Some of you have been giving me great info as I start to load and shoot my own stuff.....many thanks! It's kind of frustrating though because sometimes I shoot one bullet through the hole of another at 100 yards and it makes it hard to see....then I have to walk to the paper target, only to find out that my groups are >1/8th inch!!! It was much easier shooting factory ammo because they would be all over the target and I could see them through my scope.

On the serious side....at what point does the neck resizing die come into play? Does the FL die take it's place?? Thank!!

haven't neck sized anything in years. can't see the difference in group sizes and i usually have more than one gun in a caliber

Neck sizing is appropriate when you are shooting a front-locking bolt action and you will always be shooting the reloads only in the gun in which they were originally fired. For me, that covers about 98% of my shooting.

If using conventional dies, I don't recommend neck sizing-only because you can introduce eccentricity into the case-neck alignment. It is better to "partial full length size". Using this methodology with an FL die, the case is not inserted far enough into the die to push back the shoulder, but is inserted far enough for the walls of the die to bear against the body of the case (at the shoulder junction). Guiding the case into the die this way helps assure proper body/neck alignment. Of course, the dimensions of some dies as opposed to some chambers may not lend themselves to PFL sizing.

With a true neck-sizing die like the Lee Collet die or an "S" die you can size only the neck, or even just the upper portion of the neck like some benchresters do, and still maintain good concentricity.

The advantage in either neck or PFL sizing is that you have much less working of your brass, which avoids potential problems like head separations. It also creates less opportunity for the brass to stretch upon firing, so you can go longer between trimmings, and sometimes eliminate trimming entirely for the life of the brass.

Neck sizing can improve accuracy, but in most hunting rifles the difference between neck sizing and FL sizing is negligible, with the advantage sometimes going to FL sizing. Experiment to see what works best in a particular rifle (it can vary from gun to gun). But I would NEVER full length size when it is not required, simply because overworking the brass shortens its life and gains nothing over PFL sizing. Some shooters will point to the ease of chambering FL sized cases. This is a specious argument, as properly loaded PFL or neck sized cases chamber just as easily.

I do not own a neck sizing die. I do what is now called Partial Full Length sizing although I will debate the correctness of that term.
I set my dies up to fully resize the case and then I have a washer about the thickness of a dime with a hole in it large enough that it will fit over the threaded portion of the resizing die.I put this washer between the press and the lock ring of the die and tighten the die down. I am now neck sizing or PFL sizing. I do this until the case is blown out enough that chambering is a bit stiff and then I remove the washer, full length resize the cases and start over. Sometimes a small "doughnut" will form at the base of the neck against the shoulders. This does no harm and if anything helps align the case in the chamber.
I F/L resize all ammo I am taking big game. hunting. I will sacrifice a bit of accuracy for the positive assurance of flawless feeding and chambering.

I do own and use neck sizing dies for a few of my "target" rifles.
BUT. If you are getting 1/8th inch groups from your rifle/ loads I would be VERY reluctant to change.
If you just want to try neck sizing to see what happens. Have at it. But (again that word) I would be quite surprised to see any improvement over what you already have accuracy wise. In fact you may get worse results.

muck

I had a FN Mauser with commercial action rebarreled to 264 Win.Mag. a couple years ago and the chamber is such that a F/L sizer die has to move the shoulder back a loooong way in order to size the neck of the cases. I bought a neck sizing die for it and find case sizing much easier. I think this is more common with cartridges that headspace on the belt, such as all of the Winchester magnums except for the short mags, rather than the shoulder like the standard caliber chamberings.

if you were to partial neck size with your full length die, size around half of the neck.

I will haveto try partiak neck sizing, it isn't a technique that gets thrown around alot here in Australia