20 replies to this topic

[rokor]

Today I finally went out and got a new PAS. I finished modding it just a few minutes ago and I think I am having a problem because I modded it too well . The seal from the barrel to the plunger is 110% airtight, and when I go to cock the gun, I have to press it up against my hip to get it to catch. I have the stock spring, a LS spring, and a RFSG spring. Without a dart in the barrel I can cock it normally but with one in, it takes too much effort. I am wondering if there is a way to fix this with still keeping the range up high. Any help is appreciated.

[diamondbacknf1626]

Did you do anything to increase the seal from the plunger head-plunger tube?

[The Nerf Devil]

I don't have a PAS yet, but couldn't you coupler it and load the barrel after cocking it?

[Rambo]

The PAS Forsaken made for me is damn hard to prime. Generally I prime it, then put the barrel in the coupler. Is that inconvenient for you? I use a speedloader barrel so it's not more than a half a second longer reload time.

[rokor]

Did you do anything to increase the seal from the plunger head-plunger tube?

I left the plunger head seal alone since it already had the two stock o-rings(Is this normal or was I just lucky?)

I would prefer to not have to worry about cocking it before I stick in the dart, just because it is easier that way. If that is what I must resort to, then I will, but I would like to work a little harder to get what I had intended.

[diamondbacknf1626]

Did you do anything to increase the seal from the plunger head-plunger tube?

I left the plunger head seal alone since it already had the two stock o-rings(Is this normal or was I just lucky?)

I would prefer to not have to worry about cocking it before I stick in the dart, just because it is easier that way. If that is what I must resort to, then I will, but I would like to work a little harder to get what I had intended.

Nope, they're all like that. It's a well made stock blaster. Far more well made than the RFSG.

Your darts must be extremely tight in your barrel for them to not vaccum into the gun while priming with the barrel on. What dart/barrel material combo are you using?

[rokor]

I am using PETG with grey foam, perfect fit. I am using a peice of 5/8 behind the coupler with a peice of 1/2 inside of that, so basically there is a peice of barrel that goes inside of the 9/16 and a peice that goes outside. The 1/2 prevent that dart from vaccuming into the plunger, and that is where I think the problem is. I am going to try puting a small peice of coat hanger inside(but level with) the 1/2, I hope that will prevent the dart from going slightly inside the 1/2and making air in-accesable from entering.

[diamondbacknf1626]

I am using PETG with grey foam, perfect fit. I am using a peice of 5/8 behind the coupler with a peice of 1/2 inside of that, so basically there is a peice of barrel that goes inside of the 9/16 and a peice that goes outside. The 1/2 prevent that dart from vaccuming into the plunger, and that is where I think the problem is. I am going to try puting a small peice of coat hanger inside(but level with) the 1/2, I hope that will prevent the dart from going slightly inside the 1/2and making air in-accesable from entering.

You're better off with one of these two options:
A. Use a speedloader like Rambo said and don't prime with a dart loaded. It's easy to get used to and is effective.
or
B. Change your stopped system so that when you push the PVC into the coupler, the back of the dart touches the stopped. Make the stopper crossing coat hangers, or something of the sort, so that like you said, it does not suck back and seal the 1/2" That is where your problem lies. The dart is vacuuming back and covering/squeezing into the end of the 1/2" making it impossible for air to get around it.

Edited by diamondbacknf1626, 04 April 2009 - 09:19 PM.

[k9turrent]

You could just too weak?

but the 1/2 is creating a perfect seal, you guessed right

[TantumBull]

You could drill a tiny hole in the barrel, and cover it with your finger while shooting. I wouldn't do it, but it may be something to consider.

Edited by TantumBull, 04 April 2009 - 09:45 PM.

[nerkum]

Just add a check valve to your coupler. Air gets in, but won't go out. Right now you are just creating a vaccum in your plunger tube with your air tight seal.

[diamondbacknf1626]

Just add a check valve to your coupler. Air gets in, but won't go out. Right now you are just creating a vaccum in your plunger tube with your air tight seal.

Wow, that's a really good idea. I'm surprised I've never seen this done. It's like Tantum said; drill a hole. Except the check valve serves the purpose of covering it with your finger when you fire. I really like this idea.

[rocketninja]

Yes, this happened to me. It is because the catch spring is too strong.

[rokor]

Yes, this happened to me. It is because the catch spring is too strong.

No, just no...

[diamondbacknf1626]

No reason to ADD a check valve.

If you're sure you won't ever want vacuum loading, put a notch or two in the plunger head, just like airgun pumps have. The o-rings will then form a check-valve directly.

The only problem with this is that there are two o-rings, so there is no room for them to slide along the plunger head giving the effect that it has on pumps in air guns.

[TantumBull]

No reason to ADD a check valve.

If you're sure you won't ever want vacuum loading, put a notch or two in the plunger head, just like airgun pumps have. The o-rings will then form a check-valve directly.

The only problem with this is that there are two o-rings, so there is no room for them to slide along the plunger head giving the effect that it has on pumps in air guns.

They don't necessarily need to slide. As long as the front o-ring doesn't seal properly against the notches, it should work.

Rokor, have you considered just vacuum loading it?

[diamondbacknf1626]

No reason to ADD a check valve.

If you're sure you won't ever want vacuum loading, put a notch or two in the plunger head, just like airgun pumps have. The o-rings will then form a check-valve directly.

The only problem with this is that there are two o-rings, so there is no room for them to slide along the plunger head giving the effect that it has on pumps in air guns.

They don't necessarily need to slide. As long as the front o-ring doesn't seal properly against the notches, it should work.

Rokor, have you considered just vacuum loading it?

Oh, ok. I wasn't quite sure of the system with that. I thought the purpose was that when you pushed in, the o-ring slid to the full side (without the notches) and sealed it, and then when you pulled, it slid to the side with them, and it didn't allow for a good seal. Then yeah, this idea would work really well. I may even do that in mine.

[rokor]

Thanks for all the help guys. Should I cut the notches on the top or bottom of the plunger head?

[diamondbacknf1626]

Thanks for all the help guys. Should I cut the notches on the top or bottom of the plunger head?

I would think top, but don't take my word for it. My logic behind it is that if you have them on the front, when you pull it back, the o-ring would move to the front, or would create the bad seal at the front, and when you fired, the pressure would be towards the back, intact portion of the plunger head. Similar to how a pump works. The notches are on the front end.

[TantumBull]

rokor: top, the bottom will ruin your gun

diamond: You're actually partially right. In a nerf pump, there is actually a ridge, so when pumping, the o-ring is pushed up the ridge and pressed against the tube. When retracting the pump it moves the other way and the diameter gets thinner, so when the o-ring hits the notches it still won't be able to hold a perfect seal aggainst the tube.

Basically a culmination of what we're saying. I think it may work without the slant, just not as effectively.

[diamondbacknf1626]

rokor: top, the bottom will ruin your gun

diamond: You're actually partially right. In a nerf pump, there is actually a ridge, so when pumping, the o-ring is pushed up the ridge and pressed against the tube. When retracting the pump it moves the other way and the diameter gets thinner, so when the o-ring hits the notches it still won't be able to hold a perfect seal aggainst the tube.

Basically a culmination of what we're saying. I think it may work without the slant, just not as effectively.

I had remembered something involving the ridge that you're talking about. I was always curious how it applied. I understand now, alright. I think this would actually be pretty cool in the pas, it would solve vaccum loading problems.