Case capacity of new Bertram vs fire-formed Bertram brass

[larryo_1]

Well, I said that I would post this info when I got it so here it is.  Today I got a box of very spendy new Bertram brass and made my little comparison test on case capacity.  In comparing the Bertram cases to original cases, they are pretty darn close to the original dimensions so I got the case capacity and then fire-formed one in my rifle and got the case capacity of it.  I found that I got a 5.5 grain increase in case capacity over the new, unfired Bertram case.  Now here is what I think occurs-at least in my situation.  With this 5.5 grain increase in capacity, I get less powder compression with the Swiss 1½ that I use and I gotta pretty good hunch it gives me better stats off the Chronograph.  So there you are.  You guys can mull this over  but as far as I am concerned, what with just neck sizing my cases will last me longer and seem to help in my shooting.  did I mention that I had sent two of my fired cases down to RCBS and that they made my Trim die to match my cases and my rifle?  Oh yes, I weighed all 20 rounds in order to get two that were identical.  That stuff is not very consistent in weights.

[Chuck 100 yd]

What is the diference in capacity between a fired/firefomed case and one resized in your sizer die. That would be more what I would be interested to know if it were my gun. 

[larryo_1]

Chuck:
I suppose that I could find out but as I only run them through my Trim Die to make sure about the OAL it never occurred to me to do that.  However, it would not be too hard to do but since I got all that new stuff fire-formed and ready to gol, it would have to be awhile for me to do that.  So- if you have a new case and one that you have fire-formed, check it out and then again after sizing it.  It the sizing die is anywhere near the same dimensions of the trim die there should be no difference.  In the case of my Trim die and my sizing die, there is no difference as I have my sizing die set to neck size only.

[Chuck 100 yd]

I agree larryo_1, Thats the way I do it also. Maybe just bump it a bit to give easy chambering and no more.