I have a few random ones I got with my Nelspot from Bacci. I'll bring them and you can try them out. I'm not familiar with Line SI and compatibility with other Nelson items. Could it be the cup seal? I have some extra Lapco cup seals for Nelspot/Grey Ghost. Not sure if the power tube threading is the same on Line SI.
No, I thought cup seal first and swapped it out for a new one. If I take the rear VA with PT in it off the gun and screw my tank onto it it doesn't leak, but there is some play in the PT. The PT isn't racked and looks okay from a visual inspection. It only leaks when I'm actually cocking it - not when it's at rest.
