Load change from New to Once fired brass?

CyaN1de

CyaN1de

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I just tonight fireformed the last of my new 6BR brass. (- 4 pieces)

My question is this:

With the new brass I was loading 30.5grn Varget with 107grn SMK's

Will my load change now that the brass has more capacity than it did when it was new unfired? (EDIT: This probably should have read "Will my GROUP SIZE change" rather than "Will my load change")

If it changes is it going to be a dramatic difference? ie. from 1-2" group @ 300m to 2-3+" group at 300m

Will I have to do load development all over again now that the dimensions have changed?

The measured difference in the outside of the cases is +.0015 - +.002 over what the brass was when new.
 
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Since the new case capacity is greater, the same amount of powder will produce less pressure and--all other things being equal--less velocity.

I've run into this with 30-06 that I neck size using the Lee collet dies. The chamber-formed brass has greater capacity than fl-sized or factory brass, and as a result I'm getting slightly reduced (and I mean slightly--like 40 fps slower) mean velocity.

In most practical situations this doesn't matter at all, but could have an impact on your load's POI. Only way to find out is take the new brass out and give 'er a try.
 
I have found the same, just slighty lower velocity.
And in my 6 mm PPC gun factory chamber just a slight grouping with a slight POA.
the best thing to do is load 15 rounds, 5 at what you developed the load with , 5, 2-3 grains higher and 5 more a little bit higher and see?
Some guns love neck sizing some dont, most factory rifles from what i find you wont see much diff at all, in fact my T-3 tac wants full sized and a shoots necked sized even with an adjusted powder charge .2 to .4 moa greater than necking them? You tell me why and you will be a rich man!lol
dam reloading hey, ya got to love it
 
So best I can do then is just try them out with the same load and see what happens. I thought perhaps there may have been a definite answer as to how much of a change if any.

I will be taking them out this Wednesday to test before the competition this coming weekend. Who knows, maybe my grouping will change for the better :shrug:

Richard

I had forgot to mention as well that the cases have all been neck sized using Redding Bushing Die.
 
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