Oh thank you for the photograph... I like that setup..

so I do not have to have a hole drilled in an expensive barrel.

But I have a question,

I have been looking at the picture since you uploaded it. Is that hole the transfer port?

How does the round bolt seal the air upon closing on the barrel? I am just a little bit confused. The bolt is round, and the surface of the transfer port if that is the one, is flat flush.

Thank you.