Neil Jones make them and I've got a set: Micro Dies
Neil Jones are little different than standard busing die
MICRO NECK SIZING DIE
THIS IS THE MOST VERSITLE HAND HELD NECK SIZING DIE AVAILABE TODAY. WHEN USED WITH OUR NECK/SHOULDER BUSHINGS, THE CASE NECK IS SIZED AND THE SHOULDER CAN BE MOVED BACK IN VERY PERCISE, CONTROLLED INCREMENTS. WE RECOMMEND THAT THE DIE BE ADJUSTED TO SIZE THE FULL LENGTH OF THE NECK AND SLIGHTLY BUMP THE SHOULDER EACH TIME THE NECK IS SIZED- STARTING AS SOON AS THE CASE IS FIREFORMED.
I've got 11 of Neil's neck dies but you don't have to size all the way down if you don't want to bump the shoulders. Reason he want you to bump them every time if using arbor press may not have enough leverage you have to move up to B-Square.
Here is something on the Wilson bushing
2. There are two allen screws on top of the Wilson neck die. Remove them and remove the top of the die. This will expose the recess for the neck bushing. Insert the bushing and reassemble the top to the die. The size number stamped on one side of the bushing should face up. If you want a tighter fit, place the numbers down. This will increase tension by .0003" if you are using a Wilson bushing.(Redding & Wilson bushings are interchangeable, but Redding bushings are the same size on both sides.)
-----------After seeing how much of the neck I could not re-size (and problems there in) with the FL sizing bushed die I decided to order a neck sizing die. My reasoning being that I was going to machine the FL die and might screw it up so why not have a spare neck sizer just in case, and if it worked better I might not have to wreck the FL die.
I also had to run two bushing in steps to keep the run out down to .001 anyway. Kinda anal about that even though I doubt it makes a difference, especially with me behind the rifle.
The neck sizing die sizes the neck further than my FL die, (don't know why) at this point it will work fine for my needs from what I can tell.
Having loaded for five different Reminton 700's using S-dyes with Federal, Winchester, Lapua brass, I have found the wall thickness of unturned brass to run .014"-.015". If I take your measurements with a .308 bullet loaded of .331 your case thickness at the neck is .0115". You are then sizing the case .004" under with your neck dye which is on the tight site. It's possible that the combination of thin wall, very tight neck, and partial neck sizing that this deformation is being created. With Lapua and Winchester unturned brass I have never used an S dye under .334". My bushing size is .335". No expander is used. All chamber necks are different, but if your measurements are correct, I think you might be oversizing brass that is thin walled. IMHO.
"Let us speak courteously, deal fairly, and keep ourselves armed and ready"-T. Roosevelt
While excellent accuracy's been had with Redding's full bushing dies resizing bottleneck cases that headspace on their shoulders, I think the reason they're made to size only about 3/4ths of a fired case neck is Redding felt that was the most popular way reloaders used. In my opinion, that's based on the popular belief that loaded rounds rest in the bottom of the chamber when fired. Furthermore, the belief is if the case neck next to the shoulder's not sized down, that will help center the case neck better in the chamber neck as that round rests in the bottom of the chamber; the case neck near the shoulder will rest on the bottom of the chamber neck and that puts the bullet closer to perfect alignment with the bore than if it was sized down all the way to the shoulder.
In my measurements of how such bottleneck cases fit the chamber when fired, they don't fit that way at all. The case shoulder centers on the chamber shoulder and the case neck floats clear of the chamber neck. If the case neck's not centered on the case shoulder, it will not be centered in the chamber neck. So your sizing die had better well center the case neck on the case shoulder.
I have not yet heard one post asking why this guy is using a bushing die in the first place. If you just want to neck size and neck tension is not an issue, then just use a lee neck sizing die, it does the same thing and will not threaten to cause those types of bulges.
Anyway, it looks like the neck has been put in a death grip while still riding down in the press, either the bushing is way too small and your using a hydraulic press to size the thing andor your die setup is off. SAAMI specs show there is some taper from mouth to neck-shoulder junction anyway.
You may be right.. But, what Iím getting at is this issue seems to be about neck tension. The original poster simply wanted to know what the bulge is all about, and everyone went off on a tangent about neck sizing ability of the die. Thatís all fine and dandy, but I am not a big believer in neck bushing dies unless you have a custom chamber.
Greyfox touched on it well I think Ė the bushing being used is too much down-sizing. Going with .001 increments is better served. Now, I do question where the .331 loaded dia comes from since SAAMI specifications are .343, and bushings offered by Redding for the .308 range from .335 to .343. That is consistent with SAAMI, and weíre not talking about a custom chamber either ..(I donít believe). That just may be a turned or very thin walled cases. If heís turning, AND using that oversized bushing, that just maybe the problem.
The brass flows up through the neck, and the oversizing causes brass flow to stop or at least slow down a lot. ie that bulge. I would still suggest he would get more bang for his buck and less hassle using a collet neck-sizer such as lee, and/or turning necks, .. just my 2-c anyway. Good luck!