Shoot down due to Sear pin. Need help

[fhawkeye]

Now I'm confused. Which setup is giving your the problem?

problem is when i mount it on the am/mm rail

[fhawkeye]

Make sure the sear pin in the AM/MM rail is snapped fully into place. Also, make sure it is moving freely and not bent or binding in any way.

Make sure the ULE body isn't bottoming out in the pim hole in the AM/MM rail. If it is, it could cause the bolt cycle to be slower due to slight warping of the body.

well i dont think the body is warped because the assembly fires fine when its mounted on the r/t rail (dont see how it would sit differently from rail to rail)

and the sear assembly and pin sit in place and swing freely, my suspicion is that the pin that the assembly sits on has a millimeter or so to hop up when im trying to walk the trigger hence not allowing the sear assembly to return properly, does this make sense? if so should that happen?

[athomas]

well i dont think the body is warped because the assembly fires fine when its mounted on the r/t rail (dont see how it would sit differently from rail to rail)

and the sear assembly and pin sit in place and swing freely, my suspicion is that the pin that the assembly sits on has a millimeter or so to hop up when im trying to walk the trigger hence not allowing the sear assembly to return properly, does this make sense? if so should that happen?

The body isn't warped. It bends(warps) slightly when you tighten the rear field strip screw if the front pim (body mount) is bottomed out. It doesn't take much to put it out of alignment enough to make the valve not cycle properly. It goes back to normal if you loosen the field screw.

The trigger rod can hop. It usually only does it when you tilt the gun when firing. The position of the rod is more of a function of the trigger frame. It shouldn't be different from rail to rail. I've not seen it cause any problems.

[fhawkeye]

The body isn't warped. It bends(warps) slightly when you tighten the rear field strip screw if the front pim (body mount) is bottomed out. It doesn't take much to put it out of alignment enough to make the valve not cycle properly. It goes back to normal if you loosen the field screw.

The trigger rod can hop. It usually only does it when you tilt the gun when firing. The position of the rod is more of a function of the trigger frame. It shouldn't be different from rail to rail. I've not seen it cause any problems.

i think i understand 90% of what your saying, could you go more into detail of what would cause the body mount to be bottomed out?

[athomas]

Some of the AM/MM rails have pim holes that aren't as deep. It was a problem when putting an emag stainless body on a AM/MM rail as well. The body would rock back and forth on the rail.

[fhawkeye]

Some of the AM/MM rails have pim holes that aren't as deep. It was a problem when putting an emag stainless body on a AM/MM rail as well. The body would rock back and forth on the rail.

ahhh, ok the body does rock back and forth on the am/mm rail when the front screw is not installed. what method(s) could I use to keep it from bottoming out?

[Ando]

ahhh, ok the body does rock back and forth on the am/mm rail when the front screw is not installed. what method(s) could I use to keep it from bottoming out?

Either shave the pim down or drill the rail a little deeper.

[fhawkeye]

that doesnt seem right, this is my rail, doesn't seem like the one of the rails that should give me that kind of problem.

[athomas]

I agree with Ando, you'll have to either file the pim or drill out the hole. The easiest method to make it fit is probably to file the end of the pim down.

The AM/MM rail pim holes just aren't as deep as the other rail holes. Its a depth measurement from the early automags. I don't know why they changed the distances. All the newer pim lengths since the emags and retro mags are longer.

[fhawkeye]

My thing is that it's a brand new am/mm rail which should be fitted for the newer bodies. so before I start hacking away at the metal how about this for a theory:

On a wim I tried someone else's tank on my mag today and was getting some noticeably better performance with it. I measured this persons tank output at about 850psi, I then went to measure mine putting out about 750 - maybe 800 tops.

Would a higher output psi from the tank be cause for a stronger trigger return?

edit: and to clarify by "pim" you mean the front screw? Because I did initially notice it was too long and got a shorter one.

[athomas]

Yes, a higher output take helps it return faster but ultimately if the body is loose or rocking on the rail, that would be the biggest cause of cycle problems. If you did find that the screw was too long, it could affect the tension if it bottomed out in the pim (the threaded part of the body).

The brand new bodies are still made on the same specs as they were years ago.

[fhawkeye]

So it seems like it's come down to 2 things, either my tank is outputting too low of a pressure, which I just checked it's between 700-750, way too low to get any over-all good performance out of a mag, especially a reactive valve. + did a comparison on tanks while using my setup with the r/t rail and there it was a performance dip.

Or it could be the the issue with the pim, which now that I understand a little more about I don't think that is the issue, the body sits on the rail pretty snug it just slides back and forth when I don't have the front screw in (still mean its a problem?) valve seems to cycle fine the return on the trigger is just weak. And if you reference the picture I posted above it looks like AGD already milled out the pim hole for one of the newer bodies.

First I'm going to put another shim or 2 in my tank reg to get the output up to around 900ish and if that doesn't work then I will start looking more into filing down the pim, although honestly it doesn't seem like filing that down would really solve anything.

Just want to thank everyone for their input, you were all definitely really helpful. When I get the rebuild kit from Ninja in a week or 2 I'll be sure to post on how it turns out.

[athomas]

If the body sits flat it is fine. The front screw will hold it in place and keep it from sliding.

The low tank pressure will cause recharge issues, especially with level 10 bolt systems. Do you have a ULT in the valve as well? Lower pressure combined with a ULT would be even worst.

[fhawkeye]

If the body sits flat it is fine. The front screw will hold it in place and keep it from sliding.

The low tank pressure will cause recharge issues, especially with level 10 bolt systems. Do you have a ULT in the valve as well? Lower pressure combined with a ULT would be even worst.

yeah ULT, must have been the problem all along. Just recently had my tank replaced too so they probably just accidentally sent me one with a low output. Ninja had to replace a lot of tanks recently so it makes sense.