Help Needed For First Semi-Aiuto Project

[Air2theBrain]

Will do thanks Jack i'll screw the plug in there and cap it off.

[Air2theBrain]

Almost managed to piece her together today, just couldn't find the right threaded barrel i was after.


Trigger has replaced the slide valve which will be much better, will be fun making another trigger for it eventually.


Just did another mock up for these pics, found some nice 1/2" copper tube, but finding smaller was impossible today so its been ordered on line.


Might make a 1/2 barrel so i can at least have some plinking fun and make a mag for it until the 6mm stuff arrives, but looking forward to getting some single shots off before anything.

I wanted to ask you guys about this Scepter foam ball blaster. As powerful as it seems, it only fills to 20psi before the PRV kicks in, giving 4 shots at 5psi each in semi-auto before it needs to be pumped up again.

Would there be any way to increase the psi by each shot you think?
I thought tank expansion, etc would make no difference, i was thinking the valve that moves with the trigger, could that be possibly modified to increase the psi?

[jackssmirkingrevenge]

Would there be any way to increase the psi by each shot you think?
I thought tank expansion, etc would make no difference, i was thinking the valve that moves with the trigger, could that be possibly modified to increase the psi?

Have you seen this nerfhaven thread?

[Air2theBrain]

Yep seen that one before, it doesn't help at all..very backward barrel mod was done to that blaster, but nothing was said about increasing psi. If the tank had the OPRV plugged and reinforced then more shots could then be achieved but it would still only fire at 5psi per shot...i'm sure if i opened it right up and saw how it worked something maybe could be done..

New trigger doesn't work sadly, its leaks once air is applied...sure i have my trigger on the right way around...?


The valve that the trigger is pushed onto, air just gushes from the inside of it.

[jackssmirkingrevenge]

New trigger doesn't work sadly, its leaks once air is applied...sure i have my trigger on the right way around...?

Which type is it?

[Air2theBrain]

The picture on mine looks different to the ones you showed, didn't know their were variances in these triggers

[Air2theBrain]

I thought it was possibly damaged, etc, will swap attachments over when i can to hopefully hear a difference.

I taking a guess here..but it has to be de-energized diverter because its a 2-way?

[jackssmirkingrevenge]

You need to figure out which port does what. The easy way to do it is to simply blow into each of the ports with the trigger in its rest position. The port which is blocked is the one that you will leave unconnected. Now blow again into this port with the trigger pressed. The port where the air exits will be the port that you connect to your QEV pilot. Connect the main air supply to the third port (the one that is blocked when the trigger is pressed).

[Air2theBrain]

Ah thank you!

Had it around the wrong way

I was going from a forum pic and was certain i had it

Hopefully tomorrow i find the right spring for the mag feed and attach a barrel.

[farcticox1]

that must have been a 3 port (3/2) with an internal bleed, eg. no access to it and not able to connect to it. I used a true 3 port for my QEV trigger so I could fill through it as well.

[Air2theBrain]

Oh i see how yours is very different.

Love the trigger set up, looks great farcticox1. 8)

I just connected it earlier and seems to work really well and attached a make shift barrel for now, but my chamber is a little small.


I have this chamber i can use which is mocked up, just need another attachment for it or will find a smaller one which would suit better.


Happy i have a barrel on it now..just need more psi.

[Air2theBrain]

Did much more reading about chamber volume, have a much better one to use now.

At the moment i'm stuck here..just need one more attachment so the chamber is sealed off, if it was all steel i would have been tempted to reach for the welder so hope to find what i need tomorrow.

[farcticox1]

I go for at least 4:1 chamber to barrel volume, sure I read that here somewhere And try and keep the deadspace as small as possible if you're after performance

[jackssmirkingrevenge]

I go for at least 4:1 chamber to barrel volume, sure I read that here somewhere

There isn't really a hard and fast rule, it depends on a lot of factors. The higher the operating pressure for example, the smaller the chamber needs to be for the same power. You could also have noise constraints for example, in which case a low chamber:barrel volume ratio is ideal. The projectile type is also relevant, a light and low friction projectile will not benefit from a larger chamber volume in the same way a heavy tight one will.

This is why as always D_Hall's excellent GGDT is your friend!

[Air2theBrain]

Thanks for the replies guys.

Has been a little difficult finding the right attachments needed, agreed there is too much dead space at the moment but i will eventually clear that up, just happy its mostly all in-line. Main chamber will be directly behind the trigger so will have a nice straight air flow to the barrel.

Yes Jack for sure, really looking forward to checking GGDT out.