What would happen if stock QB with Xisico bulk end cap and pump it up to 1300 psi, 1400 psi .....
What would happen if modded QB with Mac1 extended tube and bulk end cap is pumped to 1500 psi.....
1300psi : 609.4, 584.9, 575.8, 555.3, 546.7, 528.5, 481.2, 457.2, 429.1
1400psi : 651.0, 641.8, 636.4, 615.3, 595.5, 580.6, 566.4, 547.5, 526.9, 501.7, 480.0, 455.7, 431.7
The modded QB at 1500 was a bit too high for the stock hammer spring to handle so the result was 145.1 and raise up (at 196 shot steps) to 830 remain constant about 20 shots and then start to fall gradually down about 10 -15 pershot.
Conclusion : what the gun needs is a regulator to set the pressure going in to the valve so constant volume & pressure can be supplied, therefore constant velocity can be set a bit lower than the max for more amount of shots.
QB78 PCP
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i think a big problem with the gun would be the massive valve stop.
what f/s do you get on your fully moded qb78?
i was also wondering what the barrel indents on a pellet are . how many notches are left from the rifling on a pellet if you push it through by hand? also what od is it groove to groove . sorry if you don't want to do these measurment but you have to ! . please .
what f/s do you get on your fully moded qb78?
i was also wondering what the barrel indents on a pellet are . how many notches are left from the rifling on a pellet if you push it through by hand? also what od is it groove to groove . sorry if you don't want to do these measurment but you have to ! . please .
Hi JesX,
As you were saying before adjusting the hammer spring for certain psi.
I noticed that the fully moded QB used to get co2 spikes at 830, now with pump up air, it would give steady at 830. So therefore the gun is moded max out at 830, this perticular one, with stock hammer spring. Sometime I saw hitting 839.
If there is a way to build a regulator valve infront of the gun valve, that would be nice for more consistent shots.
As you were saying before adjusting the hammer spring for certain psi.
I noticed that the fully moded QB used to get co2 spikes at 830, now with pump up air, it would give steady at 830. So therefore the gun is moded max out at 830, this perticular one, with stock hammer spring. Sometime I saw hitting 839.
If there is a way to build a regulator valve infront of the gun valve, that would be nice for more consistent shots.
Sniper, great results esp on the modded QB, 830 is a good velocity indeed and for 20 shots quite efficient.
To allow for more pressure at the valve I make a new Delrin valve head with a 45 degree tapered seat. This reduces the hammer hit required as the valve is now in effect 0.250" and of hard material which makes the valve even easier to open. I use stock spring with a 5/16" x 0.250" long hammer weight.
That arrangement is what I use in my conversions to get 1000fps from 2700 psi down.
Walter....
To allow for more pressure at the valve I make a new Delrin valve head with a 45 degree tapered seat. This reduces the hammer hit required as the valve is now in effect 0.250" and of hard material which makes the valve even easier to open. I use stock spring with a 5/16" x 0.250" long hammer weight.
That arrangement is what I use in my conversions to get 1000fps from 2700 psi down.
Walter....
Walter
Thanks for the info, sounds very good idea. Where do you get the Delrin valve head ?Voltar1 wrote:Sniper, great results esp on the modded QB, 830 is a good velocity indeed and for 20 shots quite efficient.
To allow for more pressure at the valve I make a new Delrin valve head with a 45 degree tapered seat. This reduces the hammer hit required as the valve is now in effect 0.250" and of hard material which makes the valve even easier to open. I use stock spring with a 5/16" x 0.250" long hammer weight.
That arrangement is what I use in my conversions to get 1000fps from 2700 psi down.
Walter....
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- Supporting Member 2013
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- Joined: Wed Sep 14, 2005 9:47 pm
- Location: 123 gun street Nova Scotia
you really need a lathe when working with delrin . it will seat perfect but it must be cut perfect . usually my valve pins are .02 bigger then the hole it's covering and flat to flat seal . lots of plastic companys sell it . it's $1.30 /foot in 3/8'' . i think there are 3 places in TO.
to regulate it , i would go with a restriction in the valve . so only what is in the valve gets dumped . a slower fill hole in the back of the valve . this suck if you have allready drilled it for co2 flow.
to regulate it , i would go with a restriction in the valve . so only what is in the valve gets dumped . a slower fill hole in the back of the valve . this suck if you have allready drilled it for co2 flow.
Yes, I was thinking something like that at the begining a regulated valve or hole at the gun's valve. Don't worry I got more of those valve housing for experiments.jezX wrote:you really need a lathe when working with delrin . it will seat perfect but it must be cut perfect . usually my valve pins are .02 bigger then the hole it's covering and flat to flat seal . lots of plastic companys sell it . it's $1.30 /foot in 3/8'' . i think there are 3 places in TO.
to regulate it , i would go with a restriction in the valve . so only what is in the valve gets dumped . a slower fill hole in the back of the valve . this suck if you have allready drilled it for co2 flow.