That’s fascinating! Thanks for posting. How was the adapter attached to the end of the barrel?
The adapter is a 1/2 x 20 female thread to 1/2 x 28 male thread ... it is screwed onto the barrel and can be screwed off when not in use. I threaded the barrel in 1/2 x 20, to recieve the adapter, then ground down the adapter to fit through the opening in the slide and into the spring which cycles the slide.