Did a bit more work on my 2560 HPA....

Did a bit more work on my 2560 HPA....

Joined: February 17th, 2010, 3:30 am

June 30th, 2012, 10:29 pm #1

Tried the new valve and found out that the larger throat required a stronger hammer strike to open it at over 1600 psi.... That's not surprising, so I made a longer RVA (power adjuster) to house a QB 78/9 hammer spring and now have enough hammer strike for well over 2000 psi.... I recorded the following velocities at 2000 psi....

25.3 gr. JSB Kings - 990 fps = 55.0 FPE
30.9 gr. H&N Baracudas - 940 fps = 60.6 FPE
35.3 gr. EunJin Domes - 900 fps = 63.5 FPE
41.7 gr. EunJin Points - 855 fps = 67.7 FPE

This is 10% more than I've ever had before with a 22XX based PCP.... and within 10% of my Hayabusa.... I'll be taming this thing down eventually to conserve air, right now it's pretty much running wide open.... Anyway, I guess the new valve works as intended.... grin....

Incidently, it flows enough air to hit 750 fps at 850 psi.... and 900 fps at 1400.... with JSB Kings....

Bob
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Joined: April 28th, 2010, 12:23 am

June 30th, 2012, 10:41 pm #2

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Joined: December 14th, 2010, 5:08 am

June 30th, 2012, 10:43 pm #3

Tried the new valve and found out that the larger throat required a stronger hammer strike to open it at over 1600 psi.... That's not surprising, so I made a longer RVA (power adjuster) to house a QB 78/9 hammer spring and now have enough hammer strike for well over 2000 psi.... I recorded the following velocities at 2000 psi....

25.3 gr. JSB Kings - 990 fps = 55.0 FPE
30.9 gr. H&N Baracudas - 940 fps = 60.6 FPE
35.3 gr. EunJin Domes - 900 fps = 63.5 FPE
41.7 gr. EunJin Points - 855 fps = 67.7 FPE

This is 10% more than I've ever had before with a 22XX based PCP.... and within 10% of my Hayabusa.... I'll be taming this thing down eventually to conserve air, right now it's pretty much running wide open.... Anyway, I guess the new valve works as intended.... grin....

Incidently, it flows enough air to hit 750 fps at 850 psi.... and 900 fps at 1400.... with JSB Kings....

Bob
and how do you shape the inside of the valve for it to seat on? like the crosman and benji valves all have sort of a raised cone shape inside to seal on.. what would work best or better?
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Joined: February 17th, 2010, 3:30 am

June 30th, 2012, 10:55 pm #4

running on basically a stock Disco (cone shaped) seat.... but the throat was drilled out to 1/4".... That brought the seat to nearly a knife edge to I JUST flattened it a touch with an end mill (maybe a 0.020" flat) and then spun the poppet against it with an electric drill (chucked the stem in the drill and pulled gently) to polish the seat....

There are photos and a description of the project here.... http://www.network54.com/Forum/275684/m ... +2560+HPAs

Bob

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Joined: January 17th, 2010, 12:03 am

July 1st, 2012, 4:17 pm #5

Tried the new valve and found out that the larger throat required a stronger hammer strike to open it at over 1600 psi.... That's not surprising, so I made a longer RVA (power adjuster) to house a QB 78/9 hammer spring and now have enough hammer strike for well over 2000 psi.... I recorded the following velocities at 2000 psi....

25.3 gr. JSB Kings - 990 fps = 55.0 FPE
30.9 gr. H&N Baracudas - 940 fps = 60.6 FPE
35.3 gr. EunJin Domes - 900 fps = 63.5 FPE
41.7 gr. EunJin Points - 855 fps = 67.7 FPE

This is 10% more than I've ever had before with a 22XX based PCP.... and within 10% of my Hayabusa.... I'll be taming this thing down eventually to conserve air, right now it's pretty much running wide open.... Anyway, I guess the new valve works as intended.... grin....

Incidently, it flows enough air to hit 750 fps at 850 psi.... and 900 fps at 1400.... with JSB Kings....

Bob
you are around to give smucks like me hope and the encouragement to keep fiddling and having fun with this hobby.

Really great numbers! Especially the low pressure numbers! I'm not really into the high fps right now as paper punching is the extent of my shooting, but wow!!

Rich
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Joined: February 17th, 2010, 3:30 am

July 1st, 2012, 5:26 pm #6

~850 fps (40 FPE) at 1200 psi and ~800 fps (36 FPE) at 1000 psi....

Bob
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Joined: December 14th, 2010, 5:08 am

July 1st, 2012, 7:34 pm #7

would that be possible with co2?
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Joined: February 17th, 2010, 3:30 am

July 1st, 2012, 8:53 pm #8

to be similar in performance to CO2 at 70*F in other guns.... This gun shoots about 700 fps (28 FPE) at 700 psi, so I would think that would be about right for CO2....

Bob
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Joined: December 29th, 2009, 3:08 pm

July 4th, 2012, 11:09 am #9

Tried the new valve and found out that the larger throat required a stronger hammer strike to open it at over 1600 psi.... That's not surprising, so I made a longer RVA (power adjuster) to house a QB 78/9 hammer spring and now have enough hammer strike for well over 2000 psi.... I recorded the following velocities at 2000 psi....

25.3 gr. JSB Kings - 990 fps = 55.0 FPE
30.9 gr. H&N Baracudas - 940 fps = 60.6 FPE
35.3 gr. EunJin Domes - 900 fps = 63.5 FPE
41.7 gr. EunJin Points - 855 fps = 67.7 FPE

This is 10% more than I've ever had before with a 22XX based PCP.... and within 10% of my Hayabusa.... I'll be taming this thing down eventually to conserve air, right now it's pretty much running wide open.... Anyway, I guess the new valve works as intended.... grin....

Incidently, it flows enough air to hit 750 fps at 850 psi.... and 900 fps at 1400.... with JSB Kings....

Bob
how does that affect your trigger?

on my 22XX grip frame the harder the hammer spring the worse the trigger pull.

How are you overcoming that? Are you using the new drop sear trigger?
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