Load difference in New Cases and then Neck Sized

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23 October 2011, 18:50

muygrande

Load difference in New Cases and then Neck Sized

Do you often find that your powder weight needs to increase/decrease in order to repeat groups after firing new brass and then moving to a neck sized case both being fired in the same rifle, etc?

23 October 2011, 19:14

mho

No, I tend to run the same loads in new vs. fired brass - although fired brass (normally) has a larger capacity.

- mike

*********************
The rifle is a noble weapon... It entices its bearer into primeval forests, into mountains and deserts untenanted by man. - Horace Kephart

24 October 2011, 03:30

Jim C. <><

I've never seen any difference; new or FL sized cases will be the same size as fired cases far below peak pressure. Seems the chamber is the limiting factor in "capacity."

24 October 2011, 06:42

jeffeosso

i have seen POI shift, and have seen vel differences in unfired vs neck sized...

opinions vary band of bubbas and STC hunting Club

Information on Ammoguide about
the416AR, 458AR, 470AR, 500AR
What is an AR round? Case Drawings 416-458-470AR and 500AR.
476AR,
http://www.weaponsmith.com

24 October 2011, 20:36

mho

quote:
Originally posted by jeffeosso:
i have seen POI shift,

Yes, I also keep new and reloaded cases separate, but I still run identical loads in either. Often my load developments start with new cases and end up with the same brass reloaded 1-X times.

It is rare that I'm ready to measure velocity when I'm still shooting new cases, but I guess it could happen.

- mike

*********************
The rifle is a noble weapon... It entices its bearer into primeval forests, into mountains and deserts untenanted by man. - Horace Kephart

24 October 2011, 20:44

Stonecreek

There should be negilible velocity difference between new and fired cases. The volume of the pressure cotainment vessel is determined by the chamber, not the case.

Point of impact depends on loading technique, case preparation, and perhaps even the configuration of your chamber.

26 October 2011, 01:27

Jim Hundley

I have found that the velocity increases a bit on the second firing. Don't know why except maybe some of the pressure goes to expand the case on the 1st firing instead of all the presure behind the bullet on the second loading.
I usually gain around 35 fps. on the second firing with the same amount of powder. I could be wrong, but that is my $.02 worth !

26 October 2011, 06:43

hm1996

quote:
Originally posted by Jim Hundley:
I have found that the velocity increases a bit on the second firing. Don't know why except maybe some of the pressure goes to expand the case on the 1st firing instead of all the presure behind the bullet on the second loading.
I usually gain around 35 fps. on the second firing with the same amount of powder. I could be wrong, but that is my $.02 worth !

+1

Regards,
hm

2 Chronicles 7:14:
If my people, who are called by my name, will humble themselves and pray and seek my face and turn from their wicked ways, then will I hear from heaven and will forgive their sin and will heal their land.