QB78d long Co2 tube

[rsterne]

Actually haven't a clue, never been up to those pressures.... You would certainly need to lean on the hammer spring quite a bit to be able to utilize a 3000 psi fill without the velocity dropping like a stone because of valve lock.... It is POSSIBLE you might get there by shimming the stock spring to the maximum, maybe combined with shortening the back of the hammer and the spring guide.... but I wouldn't guarantee it.... I had about 1/8" more preload available on the hammer spring than what I needed for 1600 psi on the last QB I did.... I have no idea if that would be enough for 3000 psi or not....

If you can't get there with a stock hammer spring and shimming (or using an RVA) then you would have to find a stronger spring.... The only one I have found so far that will fit is a 0.360" OD x 0.059" wire Trakar spring and it is too big to fit in a stock hammer.... Since they are hardened, now you are into making a new hammer to fit the bigger spring.... and on it goes....

As far as the safety of the valve attachment system, I would have to do the math on that to determine the safety margin (if any) at 3000 psi....

Bob

[just missed]

Planning on sticking with Co2 and in the event I as to try HPA wouldn't fill high pressure, staying under 500 fps. Even with the bulk filling Co2 I will be working with a crony to keep it under and looking for advise on how to keep it there.

[SeanMP]

Bulk filling C02 you should see no real difference in FPS from what you have now unless you overfill it by supercooling the tube and doing a hot fill.

(Bob opened my eyes to this and it can end in disaster)

I run mine on HPA at 1600 psi in the 500fps bracket because this velocity works well for a target rifle. You do need to back off the spring and/or restrict the port to stay at 500 with HPA.

But the shot count is great even on the stock tube.

[remtom1200]

I wish I could give some helpful advice but I modified my valve for power, and added the velocity adjuster to control it from a 35 shot plinker to a 9 shot monster(and that doesnt take many turns). Should you make it breathe a little too freely the tranfer port is a place to concentrate on regaining shot count.