Head stud question

I have a broken head/barrel stud which i have successfully drilled out . Part No. NMT2161. 5/16 x 26 tpi.
The question is ; is it a BSC (cycle) or a BSB (brass) thread ? The difference is the thread angle .
I need to find a tap to clean the last of the old stud out.
Thanks Col

Your thead is a 26tpi BS (cycle) thread, be very careful how you drill and tap this fastener. There are several services that will restore your threads.

RS

I think Leo at Memphis Motor Werks takes out the barrel studs and uses helicoil inserts to strengthen the threads. Don't know in OZ where you can get that done, but surely someone does it. There seem to be plenty of Nortons there.

Dave
69S