I'm going to air up my capped valve pump when I get home. I believe AThomas' numbers but swear mine is running closer to 600to the valve. I might be mistaken though. I do remember when I was running it on 12ies and had the valve devolumized that it was running even higher to get FPS in the correct range.
Timmy J was running his straight from an adjustable tank reg. As long as its adjustable enough and consistent enough an adjustable tank reg will work.
I aired up on my capped pump and am currently running about 540psi and a little hot. Shots are in the 285-294 range. On my way back out, so I can do some more checking later if needed. Level 7 bolt, freak bored barrel and I don't really underbore.