Going from new brass to once fired

[The Oregonian]

I have shot a few hundred rounds of new Nosler brass in my recently built custom in 30-06. My load is 57.2 H4350, Rem primers, Nosler BT 180gr at 3.684 CBTO....this gives me around 2810 FPS.

I just finished resizing the first half of my brass...is it unusual for the same load to work? I would expect to pick up a little velocity as the cases are fire formed, so does that likely imply that I should drop my charge weight to get back to prior velocity, which is where the best accuracy has been?

Or any other rules of thumb? Or is it a crap shoot as to how the load will perform in fire formed cases? Or is any change expected to be minimal and the same load often works?

Thx in advance.

 

[FEENIX]

I have shot a few hundred rounds of new Nosler brass in my recently built custom in 30-06. My load is 57.2 H4350, Rem primers, Nosler BT 180gr at 3.684 CBTO....this gives me around 2810 FPS.

I just finished resizing the first half of my brass...is it unusual for the same load to work? I would expect to pick up a little velocity as the cases are fire formed, so does that likely imply that I should drop my charge weight to get back to prior velocity, which is where the best accuracy has been?

Or any other rules of thumb? Or is it a crap shoot as to how the load will perform in fire formed cases? Or is any change expected to be minimal and the same load often works?

Thx in advance.

That's pretty long CBTO or COAL for a .30-06 ... 2.684" perhaps?

Here's my .300 WM with 200 NAB ...

If I understand you correctly, you are expecting more velocity in once fired brass (>2810 FPS) for the same powder charge/load configuration as virgin brass (2810 FPS)?

 

[Rich Coyle]

I proved beyond a doubt full length sized ammo is slower than neck sized ammo. Your first loads might be about like full length sized brass. I would not change anything.

 

[The Oregonian]

The CBTO includes the Hornady tool that fits on the calipers...my COAL is closer to 3.2.

I don't know what to expect with once fired brass. My thought process was that some of the energy from the detonation would go to sending the bullet rather than growing the new brass, but on the other hand, it likely has a larger case with same powder charge, so maybe the FPS goes down.

Just curious to know whether the recipe would be likely to stay somewhat consistent or if a certain amount of tweaking may be needed.

 

[The Oregonian]

I proved beyond a doubt full length sized ammo is slower than neck sized ammo. Your first loads might be about like full length sized brass. I would not change anything.

I used a Whidden custom full length sizer with bushing for neck sizing...I think you are saying that things are not likely to change much...will be shooting these this weekend most likely so will find out for myself...just trying to get some info from those who have gone through this before.

Thx

Tom

 

[Barrelnut]

Might be good to only neck size for the first three firings, since the brass does not always stretch to the full length of the chamber on the first firing. Once they get hard to chamber, you know you have found the end of the chamber. Then setup the full length die to just bump back 2-3 thousands. This will help the brass last longer and aid in keeping the bullet aligned in the chamber. Also might try not resizing the full length of the neck. only the first half to two thirds. This can also help with bullet alignment.

I doubt speed will be much different after resizing once shot brass. Really just depends on how much it stretched and how much it was set back. Pressure can be less if there is now more air space in the chamber. Grouping might be more accurate since alignment in the chamber may now be better.

 

[Greyfox]

I have shot a few hundred rounds of new Nosler brass in my recently built custom in 30-06. My load is 57.2 H4350, Rem primers, Nosler BT 180gr at 3.684 CBTO....this gives me around 2810 FPS.

I just finished resizing the first half of my brass...is it unusual for the same load to work? I would expect to pick up a little velocity as the cases are fire formed, so does that likely imply that I should drop my charge weight to get back to prior velocity, which is where the best accuracy has been?

Or any other rules of thumb? Or is it a crap shoot as to how the load will perform in fire formed cases? Or is any change expected to be minimal and the same load often works?

Thx in advance.

I have found that it is a crap shoot since chambers , cartridge design, and loads are variables. What I like to do is test the POI, accuracy, velocity, and ES of each, new, FL, and neck sized brass of a specific brand, load, and rifle chamber. I'll note the differences. I have had a few rifle/loads that have shown no material difference. While this is great, it is generally not the case. Interestingly, this is the case with my two LR 6.5x284's using Lapua brass, new or fired. Generally though, I have experienced a tendency for fired brass to have a slightly lower velocity, but tighter ES with a variety of my rifles/calibers over the years.

 

[FEENIX]

I doubt speed will be much different after resizing once shot brass. Really just depends on how much it stretched and how much it was set back. Pressure can be less if there is now more air space in the chamber. Grouping might be more accurate since alignment in the chamber may now be better.

^^^ I have similar personal experience. ^^^