Hi ratbuster2240, very nice Blue Streak! Congratulations.
They don't have an adjustable piston, that's an upgrade by Ped.
I have a small business in resealing Sheridans and Benjamins here in the Netherlands (more of a hobby tbh lol) and I usually get about 600 ft/s on 8 pumps, using 13.73 gr JSB's.
Bought this Silver Streak cheap a few weeks ago. The fact that it was scoped should have set the alarm bells off: there is not only a bit of barrel separation, but also a bit of breech separation. Tried an easy repair with Loctite 380 and JB Weld on the seams, but they couldn't stand the blasts of air escaping from the tp.
So I had to separate the breech entirely. Roughen the surfaces up, degrease, degrease, degrease. Now Loctite 380 again, but on the mating surfaces instead of just the seams.
Did this with a Blue Streak before and it worked great. Fingers crossed... It's a pity that there is no way to use a scope on these without damaging the gun.