Case shortening

[BarryL]

Is it concievably possible to trim your brass to 2.160" fire then neck size and have them .007" shorter?

 

[chrisj]

Absolutely. If you fire a standard cartridge into an improved chamber...the case is usually shortened. Second...if the shoulder is moveced fwd after firing and the die pushes the shoulder back, the case length is usually shortened.

Chris

 

[BarryL]

I sized and trimmed 284 win to 6.5-284 to 2.168". Loaded and fireformed then trimmed again to 2.160" loaded and fired again. Now some are as short as 2.153". I neck sized the first 2/3rds of the brass without touching the shoulder.

 

[Rustystud]

arryL:

Just remember brass is like a liquid it will flow to the path of least resistance. I shoot LC 89 match brass in my .308. I aneal it and resize. Then fireform and resize it again then trim it. In chambers with more than 1.5 headspacing the necks some time tend to shorten up. The cases don't stretch much in a chamber that short. In hunting rifles with .003-.005 headspacing clearance you see both web and neck stretch. That brass has to go some where.
Rustystud

 

[jadams]

Barryl:
I have made numerous improved cases, I find it quite typical that after the second fireing the cases will be .015" shorter.
John

 

[BarryL]

A majority of my brass is now 2.156" to 2.158" with a few at 2.153" I figure to maintain consistancy now Im going to trim to 2.156" and neck size about 5 thou. further down the neck still well away from the shoulder. Hopefully they wont shorten any more.

 

[mikecr]

Why are you trimming?
Is it needed?
Whats the neck length of the chamber?

 

[BarryL]

Im trimming to get equal length on all brass. I have the chamber neck length in my records at home, just dont recall it off the toop of my head