Someone please inform me as to what the heck a BRA might be?
I've not encountered that as of right now.
(The cartridge, not the more ubiquitous ladies' undergarment....)
6 BR Ackley Improved....
Warning don't read the following link unless you have an extra $800 to spend....
http://forum.accurateshooter.com/threads/6br-ackley-improved-40-degree.3883715/