So Confused On Neck Sizing My 204 Round!

[The Reloader]

Bought a bag of 100 New Brass in 204.
Shot 50 so now I have 50 unfired and 50 fire formed
Measuring with the headspace gauge of my UN-FIRED case measures 3.565
Measuring with the headspace of my FIRED case measures 3.561
every case is consistant. how are my fired cases smaller from shoulder to rim that my unfired???
when I try to neck size my brass the collet does not even touch the case!! I tried screwing the die in ALL THE WAY for the heck of it press real hard now the case measurement with the gauge is 3.564???? IT GREW!!????? What the heck am i doing lol!! There is no mix up with cases or anything.
Unless The shoulder is not not touched in the collet die process. SO if this is the case I have to choose between neck sizing and choosing the correct headspace? I thought what we where trying to achieve is being able to have .02 of headspace and only having to neck size that way we keep the fire formed shape...

[sharptailhunter]

I would try full length sizing them and then see how long they are after that. Then I would shoot the full length sized cases and remeasure them to see how long they are after that. FWIW, I'm not convinced that neck sizing only in MY .204 is getting me any better accuracy. My best groups still have come from full length sized cases.

[GaCop]

Those of us load for an AR in 204 Ruger are limited to full length sizing and accuracy isn't hurt one bit.

[DoubleUp]

GaCop, how much shoulder bump are you trying to achieve when you full-length size each time?

[Jim White]

Full length sizing shouldn't affect the accuracy. The only (-) thing it does is works the brass a little more and depending on chamber #'s it may require triming down the road.

[The Reloader]

see now. People swear by neck sizing I mean it does make sence since you have a case fire formed.. How many of you get better results full sizing over neck sizing and also how many of you just bump the sholder back the .02 for headspace?

[DoubleUp]

I neck size and then bump the shoulder back between 1 and 2 thousandths with a Redding body die when the bolt begins to feel a little too stiff on closing. It takes about 4 firings for that to happen in my rifle and I generally anneal at the same time.

[Trent]

I'm still trying to figure out how your brass shrunk from base to shoulder. That just doesn't seem possible. Here is what I am thinking... maybe there is a slight difference in the shoulder angle between your chamber and the new brass. So when you fire the rounds they are fire forming to a chamber with a slightly sharper shoulder angle. This in turn allows your comparator device to fit further up the shoulder towards the body. It certainly wouldn't take much.

Then when you resized the brass it is setting the shoulder back to standard and the comparator is then resting further out on the shoulder again.

What do you think?

[The Reloader]

Trent That is a seriously genius explanation on the probable cause of the the "shrinking brass" seems like the only thing possible and DoubleUp If i neck size and than used the LEE full size die to bump the shoulder back it would accomplish the same thing right? And do you have a strategy for finding the point at which the shoulder with start to "bump" back or is this a 50 time guess and check sorta thing?? Thanx for the responces guys really helps!!! 204 reloading is far more involved than any other calibers I reload for

[GaCop]

GaCop, how much shoulder bump are you trying to achieve when you full-length size each time?

I try for at least .002" for a bolt action. I also use a small base die in 223 Rem. I'm just getting started with the 204 and am still waiting for my Forster dies to get here. I've loaded thousands of rounds for my 223 AR's and my son's using a small base die after encountering chambering problems with a regular full length die in a tighter 223 chamber. For my bolt action 223 rem (Wylde chamber) and 223 AI, I use a Lee collet die and a body die when I need to set the shoulder back on tight cases. The chambering problems I encountered with the 223 Rem was related to the base not being sized down enough causing the unfired round to jam in the chamber. The SB die eliminated that problem.

[GaCop]

I neck size and then bump the shoulder back between 1 and 2 thousandths with a Redding body die when the bolt begins to feel a little too stiff on closing. It takes about 4 firings for that to happen in my rifle and I generally anneal at the same time.

+1

[RoadKill]

The Reloader - Did your “shrinkage” happen while doing ~ lighter loads?

John Haviland has an article in the June 2011 American Rifleman telling of the broad range of velocities he has been able to achieve with a .22-250 Cooper Model 22 24” Nosler brass etc... “It is prudent to note that these reduced-velocity loads somewhat shorten cases at the shoulder”. Measured using a Hornady L-N-L Headspace Gauge, “fired with reduced loads shortened .002” at the shoulder” and “maximum loads expanded .002” to .003””. He explains “reduced-velocity loads develop enough pressure to expand the thin case walls (and shorten the case) but not enough to swell the shoulder”.

He is talking .22-250 here but it could still explain your insanity. I’m still shooting factory chambers and have mostly partial sized with full length dies with some regular neck only die experience. I have only recently acquired the doodads that allow me to measure case growth and I’ll need to start doing a better job with record keeping. In the past, for bolt guns a carefully adjusted full length die that only slightly reduced the increased bolt closing effort has worked just as well as the neck only dies that will eventually require a “bump” anyway. The Contenders need the carefully adjusted full length die always.

[The Reloader]

I dont THINK its considered a reduced load (27grains of RL15 with a 32grain V-max Bullet) But My Next Loads will be near max and i will see what I get for results Thanx for that info!

[GaCop]

GaCop, how much shoulder bump are you trying to achieve when you full-length size each time?

I was trying for no more than .002". I've since sold the AR (got tired of loosing prepped brass) and as soon as my barrel get here (26" varmint weight, 1 in 12 twist) from Northlander, I'll be converting my Savage 223 to the 204 Ruger and load development will start all over again. My 204 will be on a 110 long action using a single shot follower so cartridge length will not be an issue.

Tom

[bow shot]

FWIW, I had the same experience, brass actually shortening after being fired. Its not bad, just a little unusual. I think Trent got it right...

I can't state this as fact, but I think that any chamber dimension that is on the "big" side of a specification would allow the brass to expand into it, draw back (shorten) from one of the only unconstrained areas..like the neck.

Wow, I just confused myself...