New brass vs. fired brass "spring-back" question

[*Nine]

I'll try to keep this short.

Reloading for my new .260 I'm using the Nosler Custom brass. I'm neck sizing only with this, and using a Redding S die. To choose my bushing I seated a bullet in the new brass and then measured the diameter and subtracted .002. I ended up with a .286 bushing. I neck size my new cases and I end up with the desired .002 neck tension when I load them.

This weekend I was doing some load development, with pretty mild loads to start. This was the first firing on this brass. After getting home I went to prep that brass to load again for more testing, and I noticed that it took more effort to seat the bullet than the first time. I grabbed a few of the once-fired cases that I had neck sized and noted that they end up .004 smaller than the new cases after neck sizing. There is no spring back in the necks, once they're sized they slip right back into the bushing. These are giving me .006 neck tension now, which I imagine is not good.

I assume the brass has hardened and that's the reason for no spring-back, but is that normal after a single firing with a mild load? Is there something else at work here?

 

[Fuzzball]

Re: New brass vs. fired brass "spring-back" question

I don't know what's at work but hardend brass has more spring back than soft brass.

 

[308sako]

Re: New brass vs. fired brass "spring-back" question

Deleted in protest! Help us out here

 

[*Nine]

Re: New brass vs. fired brass "spring-back" question

I will check the outside diameter of the rounds when I get home tonight.

I actually don't know which way the bushing is in the die right now. I was unaware that there's a taper in the bushing. I will also have to check on this.

Correct. The fired cases that I have sized are sitting between .282 and .283 after running through the .286 bushing.

 

[MitchAlsup]

Re: New brass vs. fired brass "spring-back" question

If the neck is being sized more than 0.006 in a single step, the brass has a tendency to overshoot the bushing size. Thus, if you have a factory throat, yo might (probably do) need two bushings to size the necks properly.

 

[*Nine]

Re: New brass vs. fired brass "spring-back" question

It's not a factory barrel. I will also measure the neck diameter of a fired round prior to sizing tonight.

 

[bowslngr]

Re: New brass vs. fired brass "spring-back" question

I am basically a dumbass when it comes to bushing dies. I recently bought two of them. One is an RCBS Gold Medal Full Length Bushing set in 260. The other is a Redding Type S full length set in 308. In both cases I used the same method described above for selecting and ordering bushings (measure the outside of the neck on a loaded round and subtract .001-.002"), and then order the three sizes that were closest to that measurement. In both cases, I am now getting sized brass that is too small. When I measure the outside of the resized neck, it is several thousandths smaller than the bushing diameter...and yes, I am putting the bushings in right-side-up. Anyway, I don't have any answers but wanted to say that I am seeing a similar problem.

 

[*Nine]

Re: New brass vs. fired brass "spring-back" question

Which brass are you using?

 

[*Nine]

Re: New brass vs. fired brass "spring-back" question

Here are some measurements of both R-P and Nosler neck diameters.

Remington:

New case - .289
New sized case - .285
Fired case - .296
Fired case inside neck diameter - .266
Fired case after sizing - .283


Nosler:
New case - I don't have a new unsized one
New sized case - .286
Fired case - .296
Fired case inside neck diameter - .265
Fired case after sizing - .283


The bushing was in the die with the numbers facing up. Also, loaded rounds in once-fired cases are still showing that same .288 figure that I had with the new cases.

 

[*Nine]

Re: New brass vs. fired brass "spring-back" question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">If the neck is being sized more than 0.006 in a single step, the brass has a tendency to overshoot the bushing size. Thus, if you have a factory throat, yo might (probably do) need two bushings to size the necks properly.</div></div> Based on what you say here, and my numbers above, I'm leaning towards this. I suppose I could keep a bushing for sizing new brass, and a larger one for sizing fired brass.