I got my P35 back since end of november, but could only test it yesterday. The whole process almost took 12 weeks. That was long. The P35 now shoots 1 inch groups at 40 y with JSB Heavy. I'll need to practice.
Although the tech indicated the muzzle end/crown was indeed rough, it wasn't causing the inaccuracy problems. He actually even said the barrel somewhat performed better than average SPA barrels (meaning "cheap gun" barrels). A damaged breach seal however was causing a leak resulting in loss of target precision. That seal was to be seen in one of the pics I posted. There was a second issue of my DonnyFL adapter having too much thread to screw completely into the shroud,, leaving about the space of a thin fingernail, not totally lining up the moderator onto the shroud.
Eventually the breach seal was replaced and the shroud got some extra threading machined, while adding teflon tape onto the adapter's thread, fixing it securely onto the shroud. The moderator was disassembled and cleaned up from lead debris. Some 100 test shots with an array of pellet types hasn't left any new lead debris in the moderator, showing that has probably been solved.
Once the technician was done, he called me to explain what he had done. He also stated that his work would cost some 150 USD. So I insisted he 'd review that part because I only had the gun for 3 months and didn't perform from the start, showing the breach seal problem was there when I got it. As for the adapter not fitting the shroud, I actually mailed them before buying the piece, asking if it fitted the P35, which they confirmed themselves, only to see the shroud needed more threading after I damaged my moderator because of it. The tech was going to ask around and I got an email the morning after saying they were going to send me the gun back free of charge.
In the end it cost me some 40 USD in shipping fees to send them the P35. Service was free but took almost 3 months. I'm lacking baffles in the shroud, as most got wrecked, but I'll see if I can print some internals to fit (wonder if that 'll withstand the pressure), but that 'll be for another post. The muzzle end/crown is still fugly, but I don't really care, as the gun now performs as it should (6 months after purchasing it however).