I agree that T/C could have done a better job in their customer relations in this instance. I really like my black diamond with the short barrel but I have never used the 209 primer. I have been using 2f 777 and get my best accuracy with about 80 grains using a #11 cap. The replacement 209 nipple is probably less than 10 bucks.
With this type of open breech gun make sure to wear safety glasses.
Art