I have shot the 309JDJ for about 15 years and case forming is very easy. GB is on the right track, put a drop of lube on your finger and rub it in then rub the case with your fingers and run the case into a standard 308 Win die.Set the 308 die high and size and try the case in your gun to see if it will just barely close with a slight resistance. Load with a middle of the chart load for the 309JDJ. May not need to but I seat the bullet to just barely touch the riflings. Have never had any problems over the years forming cases like this.
Steve E..............
