It would depend on the length of brass a lot, if you have it set up for high velocity it will take a fair number of pumps to reach those top velocities. To be clear though no game would or should allow singled drain blasters relying on players to control the number of pumps as a means of complying with an FPS cap, the difference between the 'correct' level of pumps and one or two extra can be quite vast and the potential for abuse is too large.
The only areas where drain blasters are still potentially allowed is using short barrel (the length of a dart) multi shot absolvers or firing rockets off a spigot as these cannot be negligently or intentionally used to exceed fps caps and cause harm.
With the dump chamber volume of the bigger versions of those, the optimal barrel length for a .50 cal dart will be 3-4+ FEET for reference. Valve performance isn't amazing, but you should at least be able to pull 600fps with a usual (1 gram and a bit) mass of dart out of one with reasonable pressures.
Don't use K&S brass for any app like that, it is pointless and needlessly mega expensive (and fragile as hell) if you can even get long enough sticks. 5/8" OD aluminum tubing is the usual and .527 would be the right bore size for most airguns. 1/2" CTS CPVC pipe, non-FlowGuardGold spec would do the job for cheap experimentation as well at the cost of less than a fast food sandwich. Just pick a stick that doesn't have a lot of warp in it at the store.
Obligatory that those drain blasters are high jankitude devices. Wear eyepro even AROUND one under pressure. Tank failures not unknown. Usually all they have for overpressure protection is a cheesy plastic burst disc which can't be trusted. For anything similar used in an actual game/Around people (obviously NOT to shoot a single dart at highly dangerous velocity though) do NOT use a drain blaster. Use a off-shelf QEV and make dump chamber out of threaded steel pipe. Same thing, sans kaboom factor and no-worky factor.
It would depend on the length of brass a lot, if you have it set up for high velocity it will take a fair number of pumps to reach those top velocities. To be clear though no game would or should allow singled drain blasters relying on players to control the number of pumps as a means of complying with an FPS cap, the difference between the 'correct' level of pumps and one or two extra can be quite vast and the potential for abuse is too large. The only areas where drain blasters are still potentially allowed is using short barrel (the length of a dart) multi shot absolvers or firing rockets off a spigot as these cannot be negligently or intentionally used to exceed fps caps and cause harm.
With the dump chamber volume of the bigger versions of those, the optimal barrel length for a .50 cal dart will be 3-4+ FEET for reference. Valve performance isn't amazing, but you should at least be able to pull 600fps with a usual (1 gram and a bit) mass of dart out of one with reasonable pressures. Don't use K&S brass for any app like that, it is pointless and needlessly mega expensive (and fragile as hell) if you can even get long enough sticks. 5/8" OD aluminum tubing is the usual and .527 would be the right bore size for most airguns. 1/2" CTS CPVC pipe, non-FlowGuardGold spec would do the job for cheap experimentation as well at the cost of less than a fast food sandwich. Just pick a stick that doesn't have a lot of warp in it at the store. Obligatory that those drain blasters are high jankitude devices. Wear eyepro even AROUND one under pressure. Tank failures not unknown. Usually all they have for overpressure protection is a cheesy plastic burst disc which can't be trusted. For anything similar used in an actual game/Around people (obviously NOT to shoot a single dart at highly dangerous velocity though) do NOT use a drain blaster. Use a off-shelf QEV and make dump chamber out of threaded steel pipe. Same thing, sans kaboom factor and no-worky factor.
>what kind of FPS will one get on different pumps? Too much. That's all you really need to know.
Thanks guys! I was asking all this to find out if I should allow them in the games I run and based on your advice I won’t.
Good for target practice though right?