6br brass growth

[patchhound]

I cant figure out why my 6br Lapua brass is going over 1.560, after two shoots my oal is 1.562-1.564, my loads are not hot and none of my old brass ever got past 1.560 after many shoots. Could it be my new tight chamber that makes it grow??? I bought the reamer my `smith used, its a Clymer 703 6br rem finisher, it was new when he got it and it only has one cut,mine). Is it normal to have growth with a tight chamber or do I got problems? I just trimmed and loaded 50 rounds of 30.3 h4895, 87 v-max, 450 cci, 2.238 coal @3125fps. It`s the first time I trimmed this brass so I`ll see what happends...

Thanks, patchhound.

 

[Cheechako]

hound

Brass for a cartridge like the BR does not grow from firing. It will grow during firing but is most likely caused by the reloading process, more particularly the sizing. If you are full length sizing or bumping the shoulder you are probably over-doing it and causing some excess headspace. When fired, the brass lengthens to fill that excess headspace void. This will eventually lead to case separations if you shoot the case enough times so it is best to find the cause and cure it before it gets to that point. JMHO

Ray

 

[janderson0]

I started with 1.560 brass when new, and now after 8 firings it's at about 1.558-1.559. Never trimed.

Jim

 

[Dean]

My brass also has 8 fireings on it that started at 1.555" and is still the same lenght.I haven't had to bump the shoulders yet and I use a Wilson neck die as well the seater,hand dies and arbor press).
From what I understand an expander ball will cause the case to grow.

Good Luck,
Dean