You need to be careful with COW. Very hard to clean. For years I've used pistol powder and toilet paper. Depending on the size of the case and the amount of powder you use, it's pretty easy to get the barrel too hot. In 338 Jamison using RWS brass I used 8g Red Dot, TP and 8 cases and stop, and let the barrel cool off. I can now use RUM cases but have not tried forming those as that RWS brass is pretty good and I haven't had to replace.
