I form both in more than one step. The 20 BR is much more involved but only because of the difference in neck size at the start.
For the 20 Practical, I use a 223 Redding Comp. sizer with a 20 cal carbide button assembly. I neck down the case in two passes, with the final bushing size of .225" for Winchester brass. Lapua brass will probably prefer a .226" bushing.
As I said, the 20 BR is more complicated.
1. New Lapua 6mm BR brass - Run through 22 BR form die
2. Run through 20 BR seating die with seating stem removed
3. Size with Redding type S sizer and .235" bushing
4. " " .232" bushing
5. Run through 20 BR body die
6. Turning necks might be something to seriously consider
* All sizing steps get Imperial Sizing die wax
I didn't have any other BR dies, so the 20 BR set was the best for me. If you already have a set for something else, just play around with different stuff to neck the brass down without inducing too much runout.
Oh, you'll have to trim the brass or it probably won't chamber. Trim length will be dependent on the reamer used to cut your chamber, but I use 1.530"
Also, be prepared to jam the bullets into the rifling with the 20 BR.
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