Can the sear be removed from the system? I think so.

[Pneumagger]

I dont think a clasic valve would work due to the flow rate. Also I rely on the RT effect to get it to function without shoot down(theory). Taking the pwoer tube off an x valve takes seconds now that I know how, so the de-volumeizing inserts will take less time to install than a Level 10 carier. The x-valve I have been using can be easily done by hand without destroying the oring.

... This may work with a clasic valve like you stated above but may suffer from shoot down if the shot chamber could not stay at the 300+psi during sustained fire. The on off in a clasic mag just wont flow much air without alot of pressure behind it.

The higher the LPR pressure the harder it is to get a consistent crono, it is a very fine ballance between input pressure and lpr pressure, depending on how fast (fps) you want to shoot and how efficient you want it. If I set the LPR to high I cant get it to crono over 250, if I set it to low it will end up with hot shots and not be very accurate, or it could just runn away. Basically I turn the LPR down 1/4 turn or as far as I need to get it to hit 290. I then when cronoed at 290 I adjust the lpr up to get it to 275 ish. The LPR pressure has more to do with the true dwell than the board. Higher pressure shorter dwell, lower pressure longer dwell.

This is what the testing suggest anyway. It may all change when I de-volumize the shot chamber.

I find it interesting that the LPR pressure has more velocity effect than the dwell. It sounds like the MPA is fighting the on/offwhee milliseconds are a huge factor. I wonder if a ULT would help the ram move quicker. Someone upthread mentioned removing the MPA spring... that might help a little. Maybe use a larger air input and hose ID on the MPA-3 & QEV so air can travel quicker (or even use an MPA-5).

As far as the valve flow issue with usng a classic, I certainly think the superior flow of an Xvalve versus the AIR Valve is not a factor for a reverse mag modification.

The way the Xvalve works is that input pressure is allowed to travel directly over the on/off until the chamber is full. This causes the trigger reactivity. Once the chamber is full the feedback pressure shuts off HP input alltogether and pressures normalize between the reg and dump chamber. Air is regulated AFTER the air passes the on/off. This, along with the imabalanced on/off pin, give a lighter resistance than the initial reactivity.

The way a classic mag works is that ALL air fed though the on/off and to the dump chamber travels through the regulator. Pressure acting over the on/off pin is never really "high pressure" and this along with a balanced on/off pin create a situation where there is no reactivity. The slower flow happens because lower pressure travels through the passages to the dump chamber.

With you operating the marker in "reverse mode" the regulator likely never closes. The only thing that matters is the on/off being open or closed. That means as long as HP input can acess the top of the on/off, the valve has an incredible recharge rate. And since the regulator becomes irrelevent, the unique feedback of the RT/X regulator is not required. A Classic valve with an air passage bypassing the reg (or you could just remove the reg seat and reg pin) using a similar on/off should behave IDENTICAL a reverse Xvalve. HP air will travel straight from the NPT input to the on-off feed passage. Assuming the regulator is not effecting anything, an RT on off in the classic valve should give the reaction as the X-Valve. The only other variable would be the orifice and passageway sizes within the valves themselves - an I don't think they are drasitcally different (if anything, the Xvalve may have more restriction when flowing around the reg tube & reg seat).

One way to test whether the reg is being totally bypassed in the RT/X valve is to play with the regulator adjustment screw. If it has little or no impact on velocity, then it does not close.

See illustration... in either Reverse Xvalve sceario, there is no reason for the RT reg to ever stop flow unless you believe the dump chamber achieves full pressurization before the bolt (with no mechanical restraint) starts moving.

[hill160881]

Good illustrations. I think your right about the flow through the classic valve it self, but I still think the speed and force at which the on off pin moves down is what makes this possible. I would have to try a test and I dont currently have a clasic valve. Maybe later this week.

Without the spring in the mpa3 the marker wont cycle consistently. I also have a QEV on the ram already. The ram venting was a problem right off the bat.

[hill160881]

Well a weekend of testing and not the results I wanted. The de-volumizing inserts did not work due to them trapping a small amount of air in the shot chamber that caused all kinds of hissing after a shot, and it caused double feeding. It looks like I will need to drill port holes around the diameter of the insert and try this again next weekend. Also when I use the smaller inserts they slide back and forward in the shot chamber, causing damage, so I will have to use the longer one and trim it down, on the inside, till I get the results I want.

[Pneumagger]

Isn't the inside of an Xvalve's chamber reverse tapered - the back of the chamber is a larger diameter than the front of the chamber?
Or is actually straight walled?

Either way, why not just put oring face seals on the front and back of the devolumizer so the powertube seals them when it's screwed on? Then no air can get trapped around the outside of the spacer.

I'm pretty interested in this project (and I have a lathe)... so if you shoot me some dimensions I can machine you a spacer with oring glands. No charge, of course.

[hill160881]

Isn't the inside of an Xvalve's chamber reverse tapered - the back of the chamber is a larger diameter than the front of the chamber?
Or is actually straight walled?

Either way, why not just put oring face seals on the front and back of the devolumizer so the powertube seals them when it's screwed on? Then no air can get trapped around the outside of the spacer.

I'm pretty interested in this project (and I have a lathe)... so if you shoot me some dimensions I can machine you a spacer with oring glands. No charge, of course.

It is a reverse tapered space. I was using orings but it is impossible to get a perfect seal so porting it is the only option. It is to big anyway and I need to remove some of the volume anyway.

[magtard13]

how about milling my lvl10 bolt down like yours + the milling like xm15 had? that would make it ultralite!

[hill160881]

Dont modify the bolt unless you are removing the sear like I did.

[hill160881]

Got it, I think. At least the leaking is gone and it will crono. I wont know for sure until I go play with it.
I had to cut a oring groove in the front to hold it in place once the power tube is tightened. Also I took off a substantial amount of the inside. I managed to keep it tapered evenly using a dril to spin it while I cut it with a dremmal.

I plan to try these in both a standard mag and the reverse mag. I will post the results as soon as I get them. If they are good then I will send it to y0da900 to be replicated, so I can get several out in the community for input.

Before







After and the shorter ones will not work

[Pneumagger]

How do you remove the powertube on an Xvalve?

[hill160881]

I will tell you how I do it, but Tuna would have a seizure if he saw me doing it . So I dont recomend this method but it is the one I use. Large curved jawed adjustable pliers, a piece of rubber and a vice. Just dont let the pliers slip and it will barley be noticeable. Clean the threads after you get it apart and you can put it back together without tools. Just dont use any lock tit till you are sure you are not going to remove it again or you will loose the red oring.

[Pneumagger]

is there aleady red loctite on it from the factory?

[hill160881]

Yes so heat helps, You will most likely destroy the red oring the first time you take it off but after that you can take it off many times if you dont use any locktite

[MoeMag]

WOW! I disapear for a while to come back and find this... AMAZING.

[hill160881]

I will have final test results with the volume reducing insert tomorrow, I hope. This will be the last test for a while until I can put several cases through it in play.

[zeroaz]

Maybe I missed it earlier, but will this work with a PneuMag setup? If not can you please briefly explain why?

Thanks