Re: Lapua, up or down? 260 Rem
"If you go down then you could get a doughnut ..."
Huh? I assume you have read about it but done little or no such case reforming?
The "doughnut" you fear relates ONLY to making shorter case bodies where thicker body brass is forced into the neck. It has NO application to a simple neck-down operation such as we are discussing.
XTRA - "Does anyone have any neck thickness dimensions on necked down brass compared to Rem brass."
I doubt anyone has that as a data point! I suspect you could get close by measuring the current thickness and multiplying that by the percent of diameter change in necking the brass down, but that's only a guess on my part. I just do it and deal with whatever it is when done. On those rare occasions I do NEED to turn a neck it surely isn't difficult to do. Most such operations are done simply to clean up the thickness variations a little and I do that on all of my "precision" brass anyway.
I do quite a bit of case reforming for three cartridges just to get "tight" necks in my factory chambers . The need to turn is more determined, for me anyway, by the actual chamber neck diameter as found with a chamber cast. I don't pay much attention to the book specs for neck diameter of my finished loads, it's MY ammo and it's not to be used by anyone else.
After major case reforming of common brass, such as R-P 30-06, to .22-250, I do turn the necks after a light ream to remove any doughnut and smooth the inside. I usually turn to leave maybe .002-3" of clearance in my factory chamber necks, it does help accuracy, a little bit anyway. I have very few "flyers", which gives me a whole lot more confidence in my ammo.
Using the right dies (a Lee Collet neck die and a Forster seater), my loaded ammo with reformed brass, the runout is typically .0005-7", or pretty darn straight!
Last edited by boomtube; 10-08-2008 at 09:14 AM.