Unusual RT Pro Issue. . .Now confirmed as micromag 2k9 problem!

[sniper42]

So I have an RT Pro valve in my micromag and it has an odd issue. I posted up in the level 10 thread but I was told it is not an issue with the bolt so I thought it needs its own thread.

I've got an rt pro valve with a level 10 bolt. I initially had the original reg piston and it worked fine so long as I didn't want to shoot above 260, that is when it started leaking. So I ordered a new reg piston from tunaman. I'm using the .5 carrier. I started off with the red bolt spring. I followed all the guides and turned the velocity up until it first cycles, this happens at about 250fps. Since that is 20fps below where I want to be I thought I'd be good. Well when I try to turn up the velocity to get to field velocity, it doesn't increase at all. I can turn it in until the velocity nut bottoms out and it won't go above 250. I tried all three bolt springs and it is the same case with each one, though at different velocities. Am I missing something crucial here? I am stumped.

Someone suggested to use washers to shim the spring but this had no effect. There are about 3 full turns from when the gun starts cycling at about 250 to when the nut bottoms out. Throughout this range the velocity doesn't change. It stays at 250.

[Patron God of Pirates]

What is the output presure of the tank you are using?

[sniper42]

The issue occurs with both my draxus tank (850ish psi) and my ninja shp at 1100psi.

[BTAutoMag]

try putting a spacer inbetween your reg spring and adj nut. ghetto but it works

a washer from a hardware store works

[sniper42]

I tried that. No change. The gun still won't cycle, even if the nut bottoms out.

[sjrtk]

Are you still using the red spring? Have you tried the gold spring to see what happens?

I ask because my retro valve would cycle at 265 with the red spring one i put the gold spring in it went to 320. I had plenty of room to adjust the velocity down to 270-300 depending on the field.

[sniper42]

Yup, same issue with all three springs.

[nak81783]

Do you have both springs (inner and outer) in between the reg piston and adjustment nut? If so, consider replacing them.

Also, compare your reg pin assy with the pic at airgun.com. Are all the pieces there? Does it look like the end that is toward the rear of the marker when assembled has been tampered with (e.g. ground/filed)?


-Nathan

[sniper42]

Both springs are in place.

The reg pin assembly looks good. I did rebuild it when I first got the valve off evilbay and I made sure to put it back together correctly.

[nak81783]

1. No leaks anywhere, correct? With or without trigger pulled?

2. Did you rebuild the reg pin assembly or the entire valve? What all did you replace?

3. Diassemble the back half of the valve. Check for debris (o-ring segment, dirt, metal shavings, etc.) in front of the reg piston.

4. If #3 checks out, I am still thinking it's the springs. If this thing sat stored for 10 years with the adjustment nut bottomed out, the springs may have relaxed in the compressed state. Or maybe someone put incorrect springs in it to begin with. I'd try new springs.

However, I know it can be frustrating to buy new parts without a guarantee they will work. Does anyone near you have a properly functioning valve you could swap back halves for test? This could help you isolate the problem.

Afterthought #1. You stated you get different velocities with the different bolt springs. Please list starting velocity for each spring. I want to make sure my hypothesis is in line with the data.

Afterthought #2: Do the same debris check as #3 in the pocket that the reg pin assembly sits in. This should cause a leak if there was something in there, except maybe an o-ring, but it's another thing to check. Take a good picture of your reg pin assembly, so we can have a look.

-Nathan

[sniper42]

1. Nope, no leaks.

2. I rebuilt the entire valve. Pretty much all the o-rings were shot when I got it.

3. Double check everything for debris, nothing I could see.

4. I think my buddy has a working valve I can swap for. I'll give that a go.

I will get some chrono readings this weekend when I can test it, as well as get some pics up.

[nak81783]

I'm following this on MCB as well. I'm not sure if you have the marker with you or not. You stated there is no debris in the reg piston pocket -- good. My next question is does the reg piston slide freely (as freely as a lubricated o-ring should) in the pocket? Also, does the piston travel all the way to the bottom of the pocket, or does it stop short? If you take the regulator valve pin o-ring out (the one that sits in the face of the rear half of the valve), can you see the brass colored reg piston sitting close to the pocket that the aforementioned o-ring sits in? If not, is the reg piston out of round, nicked, gouged, or otherwise damaged? What about the pocket? Is it out of round, nicked, gouged, or otherwise damaged? Do you see anything that would prevent the reg piston from sliding to the bottom?

Other than the reg springs being severely relaxed, my other hypothesis is that the reg piston is jammed up, and when you try to increase velocity, all you are doing is pressing the springs against a jammed reg piston. It's not getting to the reg pin like it should.

A quick way to test this is open the two halves of the valve. Remove the large reg body o-ring (the one on the threads that connect the two valve halves). Screw the valve back together. On the last turn assembling the valve, you should feel some resistance. That's the reg pin hitting the reg piston and compressing the springs. You can feel what it's like when they do not hit by removing the reg pin assembly and screwing the halves back together. If you don't feel the resistance, the regulator can't do what it's supposed to. The reason you take the large o-ring out is so that you don't feel the resistance from that when putting the two halves together. Make sure the reg pin assembly is seated all the way before doing this test. Otherwise, you'll feel a "false positive" when screwing the halves together, because you'll feel the resistance of seating the reg pin assembly.

Even if this is correct, the springs might still need to be replaced. However, if you get the piston to slide freely/bottom out, the suggestion of adding a washer behind the springs should make a difference.

Wordy, but hopefully this helps. Let us know what you find out.


-Nathan

[sniper42]

I don't have the marker with me at the moment but I will be able to mess with it tomorrow. I'll give those things a try and see what I come up with.

[nak81783]

Any update on this?

Where did the other posts go? I have e-mail notifications with additional posts that are now gone. Did the Mods delete them?


-Nathan

[OPBN]

Any update on this?

Where did the other posts go? I have e-mail notifications with additional posts that are now gone. Did the Mods delete them?


-Nathan

Apparently there was sort of minor failure and a few days of posts were lost.