Gun won't fire

[philip]

I have a pieces parts frankenmag that has the following parts; RT Pro valve, Tac one body, RT Pro rail, Aluminum single trigger frame. I have replaced the internals of the valve that are not made of metal with new parts. I shot an old style RT and then an E-Mag #740 for years before moving on so I have a pretty good understanding of how these guns work and how to maintain one. I always missed my RT so I decided to piece this one together. Anyway my issue is that the gun won't cycle. I am supplying 950 psi to the valve and you can feel the tension in the trigger. When you pull the trigger you can feel the on/off pushing in but the trigger reaches it's full travel and the gun fails to fire and when you release the pressure it pushes the trigger back in place. My initial guess is the wrong size on/off pin but before I start buying extra parts I was hoping for some advice. My second idea is that someone fiddled with the pin on the sear that kicks the trigger back.

Thanks,
Philip

[Cyco-Dude]

have you tried increasing the velocity?

[Tunaman]

is the trigger rod touching the back of the trigger when gassed up?

[philip]

Thanks Tunaman and No it's not so that rules out the sear. I tried twisting the velocity piston until it bottomed out and it didn't vent gas so now it looks like the problem is in the valve. I replaced all of the o'rings in the valve so it is possible that I did something wrong. Are there any typical mistakes that would cause my problem?

[Abubaca]

I am by NO means an expert, but I recently rebuilt the valve in my first Mag, and had epic leaks! Took it back apart, put it back together, and it's been great since. I have NO idea what I did, but I didn't do it the second time around, lol.

[Sandman]

If the gun does not fire and the trigger is pressurized there's a few possibilities. Are you using a low pressure air tank? Have to ask because, that will screw you up right there.
It's possible the sear is not clearing the bolt to release it. This could involve an on/off pin length or trigger rod adjustment. It's possible the main spring is holding everything back, especially if its the heavy silver spring. You didn't mention if it's level 10 or not. Improper assembly order of the power tube can cause this. Bent shims can cause this. Bent bolt shafts can cause this. Bent rails can cause this.
Over tightening the thumb screw can cause it. Too loose of a thumb screw can cause it.
I've seen it all just trying to give you idea's to look for.

If you have another gun, does it do the same thing in both? that will tell you if it's in the valve or not.

Cya,
Sandman

[philip]

850 psi output tank. No level 10. It's a stock Retro valve. It's not the thumb screw. It has the goldish color spring. It has an inteliframe on it now and while there is tension on the trigger there is a small amount of forward travel where there is no pressure. I can't remember if it is supposed to be completely taunt. I'm pretty sure my old RT had zero slop when it was gassed up but that was 15 years ago.

[vintage]

make sure your getting full pressure to the valve. loosen the frame screw and tighten the thumb screw first to make sure the body and valve are aligned properly. credit card thickness between the back of trigger and rod. make sure your bolt face and sear face are good. does the bolt slide easily on the power tube?

[philip]

Did some of those multiple times. Sear face looks fine, the bolt looks brand new. Yes it moves freely and I put a drop of oil in there when I did the rebuild.

[philip]

Does the Tac One mainbody require the use of a longer ON/OFF pin?

[athomas]

The tac body uses the same pin as all the mags. The pin length should be 0.750"

There are a few things you can do to check your setup.

First, turn on the safety and gas up the marker. Then hold the trigger against the safety. You should have a tiny credit card gap between the back of the trigger and the trigger rod. Too much gap and the trigger won't push the sear far enough to release the bolt. If the trigger is touching the trigger rod, then the on-off won't open to charge the front chamber.

Is your rail bushing in place? Without it, you won't get proper valve to body-rail alignment.

Make sure the bolt moves freely in the body. Install the valve without the bolt spring installed. Don't air up the marker, but hold the trigger and tilt the marker forward and back to see if the bolt moves back and forth in the breach.

Next, install the valve without the bolt or spring. Air up the valve while holding the trigger. Gently release the trigger and see if the valve vents air out the front. If it does, then you know the on-off is opening when you release the trigger. You can control the leak with the trigger, so you won't lose much air.

[philip]

It's cycling now. Unfortunately the recharge rate is about 1 second. I believe it is the spring stack on the regulator valve pin assembly and or the missing dark thing from the front pictured below. It looks like it might just be a c-clip. Does anyone know the spring stack order?
10-30-2016 4-45-06 PM.jpg

[athomas]

If it is just slow to make the trigger reset, then that is bolt stick. Make sure you are using the proper length powertube spacer. Too short, and it will cause bolt stick issues which cause slow recharge. If you don't have any extra powertube spacers, add a level 10 shim between the powertube tip and the spacer.

If you are missing the c-clip, that will cause issues.

I just went to look at my assembly for reference. When I pulled it out, my orings had turned to glue and stuck, so the pin came without the same c-clip you referenced. I've never had that happen before. It caused the on-off assembly to be really difficult to get out too, because that is where the c-clip went. I had to put on new orings and a reinstall the clip onto the end of the regulator pin assembly.

If you can't find the c-clip, you should get ahold of Tunaman and get him to send you a new one. You need it to keep the regulator pin assembly together.

[philip]

The valve is slow to recharge. If I try to fire it too quickly the second shot will just barely clear the barrel. Yes I appear to be missing that C-clip and since the valve is used it made me wonder about the spring stack order. People do all kinds of dumb things to these guns.

[athomas]

The valve is slow to recharge. If I try to fire it too quickly the second shot will just barely clear the barrel. Yes I appear to be missing that C-clip and since the valve is used it made me wonder about the spring stack order. People do all kinds of dumb things to these guns.

The slow recharge could be the same problem that you were experiencing when it wouldn't fire. Its just that it now slowly leaks enough air past the blockage to actually charge the front chamber. I would start with contacting Tunaman and getting the C-clip you need. Tunaman can give you a heads up on the stacking order of the springs as well. I would try, but I don't have mine in front of me right now. I would also have to put it under the magnifier or take a high res picture and blow it up. My eyes aren't quite as good as they used to be. LOL.

Once you get the C-clip, you can continue the troubleshooting process. One thing, you might want to check is the pin length. If your valve is one of the original RT Pro valves, it may have a 0.760" pin. If it does, order a 0.740" pin and you should be good to go. The 0.740" pin is shorter than the standard 0.750" pin and will give you a shorter activation with greater ability to be reactive while still able to control the ability to be reactive.