X-Valve & RT On/Off Not Working in Automag Classic Marker/Valve

[nak81783]

I have an X-Valve in an XM Automag and just received an Automag Classic with a Classic Valve. My plan was to upgrade the Classic with a Level 10 and an RT On/Off (for the lighter pull; I understand it won't add reactivity). Before purchasing new parts, I thought I'd swap over the parts from the X-Valve to the Classic to make sure everything worked.

Every combination works in the XM Automag, but the following do not work in the Automag Classic marker.
1. X-Valve in the Automag Classic marker
2. RT On/Off in the Classic Valve in the Automag Classic marker

Rail bushings are present in both rails. Both pins measure .750". Sear rods both measure 1.985" with appropriate gap between rod and trigger.

With the aforementioned two combinations, when first airing up, I get 1-3 shots, then it chuffs a few times, then the trigger is still "pressurized", but the marker won't fire.

The only thing I can think of is the interaction between sear and on/off. The Automag Classic sear is the older "fat style" with the extra material below the sear tip area. It is about .108" thick as opposed to the XM Automag sear being .128" thick. Also the tab that pushes up on the on/off pin is .148" long compared to the XM Automag sear being .185" long ("long" direction being from aft to forward). There's obviously also much more play with the Automag Classic rail, sear pin, and sear compared to the XM Automag.

All that said, could the Automag Classic sear be drifting side to side, pushing on the pin, but not being centered in the slot of the on/off bottom, hitting the slot wall, not letting the trigger pull complete to disengage the sear from the bolt?

[nak81783]

After assembling everything without the trigger frame, so I could see how sear and on/off lined up, it doesn’t seem like what I described above could happen. The sear stays centered side to side, and the pin stays engaged with the sear through its entire travel.

The powerfeed, hopper left body is pump milled but not the rail, if that matters.

[rawbutter]

Your sear could be worn out. That's not very common, but it happens.

What kind of frame are you using with the classic?

[Tunaman]

Try tightening the field strip screw with a wrench.

[nak81783]

Your sear could be worn out. That's not very common, but it happens.

What kind of frame are you using with the classic?

Sear tip is sharp. Sear pin is a slip fit into the sear hole, no slop/play at that interface.

AGD carbon fiber frame.

Try tightening the field strip screw with a wrench.

Always do. You taught me that almost two decades ago.

[rawbutter]

Hopefully Sandman can chime in here. Your problem sounds almost exactly like a similar problem I was having with a Minimag valve with an RT on/off. My x-valve would work in both my markers, and the minimag valve would work in my ULE marker. But the minimag valve would do weird stuff in the classic marker. I even sent the valve to AGD for fixing, but when Sandman got it, the valve didn't misbehave for him. Very odd.

I ended up ordering a new sear since I couldn't think of what else it could be, but it's not here yet. I'll let you know what happens when it arrives.

[nak81783]

Luke to the rescue. Sanded bottom of RT on/off pin to achieve .740" overall length.

All combinations work now. Not sure why .750" works in Classic on/off, but RT on/off needs .740". Must be something to do with the cylindrical bottom of the Classic on/off versus rounded/slotted bottom of RT on/off. Things must just seat differently when pressurized.

XM is even running better - snappier recharge.

[Tunaman]

Luke to the rescue. Sanded bottom of RT on/off pin to achieve .740" overall length.

All combinations work now. Not sure why .750" works in Classic on/off, but RT on/off needs .740". Must be something to do with the cylindrical bottom of the Classic on/off versus rounded/slotted bottom of RT on/off. Things must just seat differently when pressurized.

XM is even running better - snappier recharge.

Over the years I have seen some of these specs change a bit. Tolerances that are a little on the high side on one batch and towards the low side on another. Sometimes these tolerances stack together in the wrong direction, hence what what you may be seeing here.