case prep ?

[Frankr]

I would like to talk/ask ? about case prep for the 6BR.
I know it has been said just take them from the box and load them/they dont get any
better than that.I agree the 6BR lapua case is the greatest brass case there is,But i
disagree with not preping them for the best accuracry. I have a friend with a no turn
neck and he just take them out of the box and loads them with good results.But I
can not do that,I even match cases for my big game hunting rifle, its hard to do it any
other way once you know about doing it. IN MY OPINION.I prefer i tight neck chamber,
i like to neck turn,but i dont turn just to make them fit,i turn to try to make them all the
SAME..I cut all primer pockets the same, i use the tool that goes in the back of the primer
pocket that makes all the flash holes the same.(afer they have been fired once)..so lets
see all the necks the same,flash holes,primer pockets,all fired once and trimed to the
same length. so every case is now the same.Now for the big one(im leaven one secret step out on purpose) WEIGHT SORTING THE CASES...now if every case is the same and i
weigh them and one case is a grain heaver..WHY?..every thing is the same they been formed to the chamber. where is a grain of weight differance at?..I think it has to be in case voulme somewere?.. so i weight sort in the 6BR to .3gr...3 tenths of a grain.. and it
has never not worked for me.. now the case that was a grain heaver was out of my group
at 100yds so where would it be at a further range?.. So i would be interested in other shooters OPINIONS on case prep if any...Now there is a great vidio on youtube by jack neary about tuning the 6ppc. Its 6 parts,and i feel its the most information on BR shooting
that i ever seen,He talks about minor differences in cases and how they would not
shoot,like .0004 stuff..neck lengths .004 difference. i feel its very imformative..and every
problem he talks about with the 6ppc and how he has overcame them...i have had every
problem he talks about,I over came them too,I shoot a 6BR..lol HA..

http://www.youtube.com/watch?v=7SZWvn68bRU

 

[RonAKA]

You can take my comments with a grain of salt, as I am not very experienced at this game, and while I can make some very tight 3 shot groups in the .1's & .2's, I have an issue with a flyer about every 10 shots. I'll have to get some pics of the targets and ask for help on that one in another thread.

But, that said here is what I did with my first batch of new Lapua cases (cardboard box - measure about 0.269" loaded). I very very lightly chamfered the inside and outside of the neck mouth. I then removed the bushing from my Forster bushing/bump die. I had bought as an option the full sized 0.243" expander ball. I fitted that ball and ran it through all the cases. I found it opened them up about 0.001". I also weighed them and sorted them into three batches, with 2-3 rejects. That was it. I did not touch the primer pockets or flash holes. After they have been fired I use the .267 bushing, and I have retained the expander ball. It is located right up near the neck in the Forster die, and just kisses the ID on the removal stroke. I feel it opens up the ID by about 0.0003" or so. My thoughts are that due to the very slight expansion, and the location of the ball, it does not contribute to runout.

I am now about to start a new batch of brass (same lot# in cardboard box), and plan to do things a little differently. Two changes. One, I am going to square the neck mouths with a trimer before chamfering. I only did that after about 4 loads on the first batch. Original plan was to wait until they were too long, but they grow so little I'm not sure when they will need to be trimmed for length. And my second change is that I plan to measure case volume after the first firing, using some fine powder, and sort them by powder weight instead of case weight.