Most cases measure around .014.
Bill, what I'm trying to help you calculate is the thickness needed for 0.002 per side (total of 0.004)
If you measure the total outside diameter of a fired 6mm Remington case, then subtract bullet diameter (approx. 0.243*) then subtract 0.004 for the neck clearance then divide by 2 you will know how thick the dimension in which to turn your RWS brass to after its been formed down from 7x57 Mauser to 6mm Remington.
The .014 you provided doesn't tell us the
diameter of your neck in your chamber.
IF you are satisfied / want all your necks at 0.014 thickness then you'll need to make a decision on whether you want to inside neck ream & then neck-turn or stick with straight neck-turning. - The issue that I see with neck reaming is it creates necks that are not very uniform as far as neck-thickness goes as the reamer will follow the path of basically least resistance in most cases.
IMO and although more work, I would neck-turn it in steps. - RWS is usually very good quality brass and it would be nice to maintain the quality & precision of it.
Another side note, once you get it formed & trimmed, be sure to check and compare case capacity against the normal 6mm Rem. brass that you have been using, as forming from 7x57 Mauser down to 6mm Rem with RWS brass which is normally thicker could possibly (most likely) have less case capacity. - Meaning you'd want to start out lower in powder charge than what you were loading for the "regular" 6mm Rem. brass.
You are welcome to P.M. me also if you want to, or we can pursue through the normal thread as other members may also have some advice.
I have formed 30-06 to 7x57 Mauser & then necked down to 6mm Rem. in the past. - This is why I mention to check case capacity on your newly formed RWS brass, so you don't load over-pressure when starting out using your new brass.
- Ron -
