I started a thread about buying an anealer to extend my brass life and came to the conclusion that i may have other issues i need to address. I have

only been loading for about 10 years, and just set up my dies as per instructions and started loading.  I dont have any other issues besides random

split necks and i don’t really hot rod my loads some are at or near max but most are mid range. They are all shot out of various AR platforms, and i

used to use small base dies but only use FL dies now (for the past 5 years) I just went and measured random brass and loaded cartridges and the

results were as follows as measured at the neck. 223/556

Loaded: Hornady brass loaded
vmax .248 average
Bthp .247

Winchester brass
Vmax .246-.2455

Lc brass
Fmj .246

Sized out of Dillon
All brass was .245-.2475

So my questions are

1. Should i get bushing dies?
2  Does this mean anything
3  do i need anymore measurements
4. What is the best way to determine bushing die needs (thinking about them for my 308 also)

Thanks for the help, and sorry for my ignorance but this is a great place to come for information, thanks again

I'm going to guess bushing dies may help it sounds like the die is possibly sizing the neck too much and then expander is popping the neck out to the .245/6/7 sizes depending on brass make.

Try removing the expander button and sizing a die w/o it see what that looks like

With no expander ball they are .237-.238

This is why your necks crack.

A Redding Type S full length sizing die is expensive but I feel it is worth the investment.  I use FL bushing dies for all my cartridges.

With them you can control the neck sizing.  This extends the life of the brass.   There are other reasons, as well, but that is one of them.

I have no problem spending money for quality. I have always looked at bushing dies but didn’t know how to pick the correct bushing, do you have any suggestions on how to best select the correct bushing. Also i would potentially need multiple bushings depending on the brass manufacturer, correct?

Remember that Dillon Trim or Sizer dies are same as using a small base sizer die.  Now, this of course, does not really affect the neck so to speak.
Each brand of brass will require a different bushing size. As the neck wall thickness varies, best measured with a ball micrometer.

The purpose of using a bushing die is to have a more uniform neck tension.

And, especially when using brass fire-formed in the chamber it is going back into.  This where it works the best.
You skip the expander ball, and use  the bushing to control the neck tension only.

The bushing size then is dependent on the platform
For a bolt gun with being single loaded you would want 0.001" neck tension
For a bolt gun with being loaded from the mag you want 0.002" neck tension
For an autoloader then you would want 0.003" neck tension

So if you loaded round measured 0.250"
you then subtract the appropriate #.

OP, the best way to figure out bushing size is take 2-3 average cases from each brand/lot you want to use bushings on, plus any specific bullets  you will use with them..size the cases, then without primer or powder, just a bare case, seat a bullet to installed OAL and measure the neck in 2-3 spots..this measurement is used to figure out your bushing..Subtract your neck tension you desire(I normally do .002" for all bolt guns and .003" for all semi's),  so lets take a .308 wm case as an example... the bullet I plan to load measure right on .308" diameter, the 3 cases from one brand/lot of cases I am going to use, when bullet is seated measure .340"/.342/.340"... So what that tells you is neck wall thickness varies from .016" to .017" on that brass.....016"+.016"+.308"= .340"...
I error on the tight side, so we will say .340" average...I now subtract my .002" for a bolt gun which gives me a bushing size of .340"-.002"= .338" bushing..So now theoretically a .338" bushing will size my necks properly..but cases vary by a bit and one bushing may not provide enough tension on every case, so I would buy at least 3 bushings for that load work...338"/ .336" and .334"..I can live with a little over sizing versus buying 20 bushings in .001" increments, but if you load several .30 cal  rifles/various brands of brass, you may end up with 5-15 different sizes all for .308 cal ammo..

I have a handfull of bushings for .308; .331, .332, .336, .338

The big ones I use for military cases.  

The smaller ones I use for Winchester/black hills cases and Lapua.  

I have at times played with lightly cleaning up necks with neck turning tools but that’s a whole nother rabbit hole of research and experimentation.

Thanks for all the replies, i will do some more measuring on various cases and see what i come up with and report back.

Be wary that after a few loads you might get work hardening and your effect after the trip through the bushing might change due springback.  BTDT, cut it too close and in time I had to anneal or step down a size.

I use Forster full length dies because Forster will hone the necks to any dimension you specify for around $12 plus shipping.

This allows you to have custom dies at a fraction of the cost. My .223 dies were honed to .2445" neck diameter. .2440" will work great too. This dimension should resize any brass you run through it and achieve approximately .003" neck tension before the expander ball comes back through. I use a .221" expander ball just to remove any donuts.

Forster full length dies produce necks with .001" runout or less in my experience due to the high wall expander they use.  I size brass for all my AR's using Forster dies.  In bolt guns, I still use Redding bushing dies.

What is the most amount of sizing you are all comfortable with per pass through the bushing?

My loaded .308 rounds with Nosler brass is .334.
To size for .002 neck tension for my bolt gun suggests I use a .332 bushing.

The neck of my fired brass is measuring .344.

That would require .012 of neck sizing.  Is that a lot for one pass through the bushing?
I recall reading in one of the posts that some are using an intermediate bushing, such as .338.

How many of you would recommend using an intermediate bushing and two passes?

Thanks!

I do 2 passes on my brass, my fired brass runs .343", I size it to .338", then further into the process it gets sized down to .334" and then final step is to run a mandrel thru it to bring it back up to .335" for loading...

This. I'm loading 243 Winchester which somewhat notorious for splitting necks, and am going strong on 7 loads using Starline brass (without annealing).

The difference in neck thickness is stark between brands and F/L dies work with all of them...

Privi brass is so thin that you need a bushing size or two below the recommend smallest size for it.