Annealed brass neck sizes too much?

[thefitter]

I annealed some cases yesterday and today I went to neck size them. I'm using, you guessed it a FORSTER bushing bump neck sizer.

I'm using a .336 bushing but all the necks are coming out at .333 ???

 

[queen_stick]

What do the necks measure before being sized?
Sounds like the bushing isn't even touching the neck. Or, the bushing is actually about .332 or so. Pull the bushing out and measure it.
Did you have this problem previously with the same bushing?
How much are you bumping the shoulders?

If anything, the freshly annealed brass should come a hair larger, because they'll tend to have more 'spring-back.'

 

[BoydAllen]

If they came out differently before annealing, using the same bushing, the difference is spring back. How are you annealing? The short version...you may need another bushing, and if the case necks are too soft, new cases. That would depend on whether your components require neck tension, greater than the annealed cases can provide, for best accuracy.

 

[Heavies]

I may be wrong, but doesn't annealed brass spring back less than the harder unannealed? I have found greater seat force on freshly annealed brass in my experience. The softer brass is sized more effectively thus giving a closer fit to the bushings.
Also, the marked .336 bushing should not be sizing all the way down to .333. .001 spring back is the usual number. Something is amiss.

 

[alf]

It does spring back less.

I find it take less pressure to seat bullets in annealed brass.

Are you measuring with a micrometer or calipers?

 

[thefitter]

What do the necks measure before being sized? .345
Sounds like the bushing isn't even touching the neck. Or, the bushing is actually about .332 or so. Pull the bushing out and measure it. It measures .336
Did you have this problem previously with the same bushing? No
How much are you bumping the shoulders? I'm not bumping the shoulders only neck sizing.

If anything, the freshly annealed brass should come a hair larger, because they'll tend to have more 'spring-back.'

I'm annealing buy hand. And I'm using some very good digital Miyouto calipers. These bushings never did this before. It's very weird!

 

[limbic]

I had a similar problem. I let them sit overnight after neck sizing and they all measured the same size as the bushing I used.

 

[queen_stick]

It does spring back less.

Wow. I've been thinking about this all wrong! I just went back and reread one of the annealing articles...

 

[thefitter]

That's interesting and makes sense but I still don't know why it did it before. And since the largest bushing I have is .336 that means I will be shooting with .004 neck tension this weekend. :

 

[in2deep]

May want to check the ones you will be using for score for concentricity and cull thru and pick out the best ones. I oversized some cases by mistake and it caused lots of runout and was noticable on paper at 300 yards with some crazy fliers.

 

[SmokinJoe]

fitter, if you have an expander mandrel or standard dies with an expander, run them throught that, then the bushing die. That may get you closer to where you want to be, especially the expander mandrel, then bushing die procedure. Good luck with it.

 

[thefitter]

fitter, if you have an expander mandrel or standard dies with an expander, run them throught that, then the bushing die. That may get you closer to where you want to be, especially the expander mandrel, then bushing die procedure. Good luck with it.

Funny you said that because that's what I did. I wanted the brass to be as uniform as possible so I full sized it then used an expander. Then I annealed and neck sized.

Got a call back from Forster tonight. They pretty much had no idea. They suggested that I try a different lube.

 

[Gearheadpyro]

I think we have two things going on here, both of which have happened (seperately) to me.

1; annealed brass is softer, and therefore won't spring back as much as slightly hardened brass (especially if it is over annealed at all).

2; as mentioned above, if you size a case down too much in one step the case seems to reach a point where it looses all elasticity and "oversizes". Almost like you pass the stress point in the metal.

I did a test on this with a large batch of twice fired .308 cases (half annealed, half not). I took the cases and ran the same number through several sizes of bushings in a redding die. For the unannealed cases anything more than a .010" size would cause the case to "oversize", for annealed cases it was more like .008" size.

 

[in2deep]

Interesting discussion as I incorrectly assumed that new or recently annealed brass was softer and more resilient and so more likely to expand or stretch back to it's original shape after sizing as opposed to older fired brass that became work hardened and less malleable and less prone or able to expand back to a larger diameter after being squeezed down in a neck bushing. Being dyslexic doesn't help either so hopefully I got it right this time.

 

[Heavies]

Fitter,
How soft is the necks on the brass? Can you easily crush the neck with your fingernail?

Please be careful. If you can easily crush with a fingernail, you may have overannealed them.
Dead soft may be dangerous.

 

[thefitter]

Fitter,
How soft is the necks on the brass? Can you easily crush the neck with your fingernail?

Please be careful. If you can easily crush with a fingernail, you may have overannealed them.
Dead soft may be dangerous.

No chance. I did it by hand. Thanks