RE: Nipples for the TC hakwen 50
Thompson Center sells their own Stainless Steel Hot Shot nipple that handles the #11 caps and it works great. I bought some at Wal Mart at their end of clearance sale. The one thing I have heard of happening with people that went to the musket cap nipple, is too much power. The result is it recocks the hammer. That can not be good for the rifle in my opinion.
I never found the #11 a problem igniting the charge and the musket caps tend to fall off easier from my tests, so I stay with what works.