De-volumizing an X valve

[hill160881]

What % of the volume reduced would be most effective? %10, %20?

[hill160881]

OOPS, :tard: wrong section.

I thought I was in the tec forum

[hill160881]

This would be a drop in de-volumeizing sleeve.

This is what I want to make but I need a starting point on how much reduction is best to get some prototypes to test with.
http://i971.photobucket.com/albums/ae195/hill160881/Temp/Projects/PICT1422.jpg

[pbjunky99]

Man you are going all out on this project. Question, do you realy have to de-volumiez the valve for your searless mag to work properly? I understand that doing this may(or may not) help with effencicy but at what cost is it just not worth it. I look forward to your end numbers though.

[hill160881]

I dont have to reduce it to get it to rip like normal but i am going for a more efficient setup and if I can do it, all the things I did can be incorporated into a kit of some kind. My goal is 1500 rounds on a 68/45

Counting the paint i am only in this for like 150 bucks.

[Ando]

One thing to take note on Tracy. The more you put in the dump chamber, the more pressure is needed to get your desired fps and since the front of the sear is no more, your spring alone might not be able to take the pressure.

So not only will you have to find that fine line between your ROF and shoot down, you now added another equation into the mix with the spring holding the bolt back. I'm no mathematician so good luck. I set my ROF on my pump mags at around 5-6 and I'm getting a good 20-25 shots off a 12 gram (depending on the 12 gram). That was all trial and error on my part. I can get my shot count up more but the ROF suffers.

Since an X-valve is plumbed differently you might not run into the shoot down problem at all but that I don't know, never tested it out. Hopefully someone that's done it can shed some light on the issue.

[hill160881]

That is why I think I will get two different ones made. One with more reduction and one with less. y0da900 on MCB said he could make two of them for me to test with.

As you said it may be a real pain to tune in the end. Right now I am at the same efficiency one mite get out of a classic mag, and only maybe 200 rounds better than a standard Ego mag.

[snoopay700]

One thing to take note on Tracy. The more you put in the dump chamber, the more pressure is needed to get your desired fps and since the front of the sear is no more, your spring alone might not be able to take the pressure.

So not only will you have to find that fine line between your ROF and shoot down, you now added another equation into the mix with the spring holding the bolt back. I'm no mathematician so good luck. I set my ROF on my pump mags at around 5-6 and I'm getting a good 20-25 shots off a 12 gram (depending on the 12 gram). That was all trial and error on my part. I can get my shot count up more but the ROF suffers.

Since an X-valve is plumbed differently you might not run into the shoot down problem at all but that I don't know, never tested it out. Hopefully someone that's done it can shed some light on the issue.
That's not true. With how he has his project set up, the dump chamber acts like a big head loss. As i said in the other thread this is due to the fact that there is a sudden expansion and a sudden contraction. If you can get rid of both of these it will up the efficiency a lot. The k-value (coefficient for each case) depends on the actual dimensions, so i don't know how much loss you're seeing, but i think it's significant. As i said in the other thread, i think this design will yield the greatest increase in efficiency:

http://i5.photobucket.com/albums/y190/rebelsk8r700/rtemag_6fps.jpg

[hill160881]

I see now from the animation what you are saying. I had it backwards in my head.

I will post this in my thread on MCB and see if he can make one like the one you have there.

Thanks

[snoopay700]

Sure thing. I've been wanting to do this project or see it done for a while, so i'm happy to help in any way i can.

[Ando]

I think were talking about 2 separate things snoop. I'm not talking about the design of his insert. Just stating that he needs to watch out how much of the chamber he shrinks.

The smaller the chamber the more pressure is needed to propel the ball and with only the spring there to hold the bolt back, the higher pressure might be too much for it.

[hill160881]

I also want to make one like I drew for a regular x-valve and see if there is any improvement there.

[Ando]

Ty might be able to help you out with that.

[hill160881]

Thanks, I am also trying to find a simple few mods to get another 140+ rounds out of a regular ego mag.

[snoopay700]

I think were talking about 2 separate things snoop. I'm not talking about the design of his insert. Just stating that he needs to watch out how much of the chamber he shrinks.

The smaller the chamber the more pressure is needed to propel the ball and with only the spring there to hold the bolt back, the higher pressure might be too much for it.
I understood what you meant, but the thing is you're still thinking of it as a dump chamber when it's not. The bolt will move when it gets to a certain pressure. If the bolt were being held back then i would agree with you, but as soon as that smaller volume reaches the pressure that will make the bolt move, it will. The only thing that decreasing the dump chamber volume will do is reduce the pressure losses (and therefore improve the efficiency), it won't make the pressure behind the bolt any higher since it's no longer restricted.

[pbjunky99]

I thought he was running this set up with the on/off closed. With that sais no air can get to the bolt untill he cycles the marker so the pressure shouldn't be an issue as long as the on/off dosnt fail and cause the marker to run a way. Or am I mistaken?

edit: Or is there a pressure point where the on/off will fail and he has to make sure not to reach that point?

[hill160881]

I thought he was running this set up with the on/off closed. With that sais no air can get to the bolt untill he cycles the marker so the pressure shouldn't be an issue as long as the on/off dosnt fail and cause the marker to run a way. Or am I mistaken?

edit: Or is there a pressure point where the on/off will fail and he has to make sure not to reach that point?

Yes but I am hoping this de-volumizing will work with a regular Mag as well.

I can max out the valve without pushing past the on off. so that is not an issue.

[snoopay700]

I thought he was running this set up with the on/off closed. With that sais no air can get to the bolt untill he cycles the marker so the pressure shouldn't be an issue as long as the on/off dosnt fail and cause the marker to run a way. Or am I mistaken?

edit: Or is there a pressure point where the on/off will fail and he has to make sure not to reach that point?
That's pretty much what i meant. However my design won't work for the standard mag, only the reversed one that he has as it will as ando said, make the pressure need to be too high to get a decent shot, but the regulator piston will vent well before it reaches that pressure. My design should make for a very efficient reversed mag though, and if you apply a similar idea (smoother transitions) to the normal dump chamber of a normal mag you may see marginal improvements in efficiency, but i don't think it would make a ton of difference.