There is no way to be certain that there is a pin or not as they are welded over, filled and then blued over to look smooth. I had to file away at the 6oclock possition for a while before I noticed the pin.
After all that work I realized that they shortened my barrel and a CETME brake would not thread on since the threading was smaller and different. I had to have a new brake custom threaded by a machinist to fix the problem.
Wish I never screwed around with the break.