RT on/off in Classic with pump trouble ..

[Motorhead]

I had a perfectly operating Classic mag pump until I installed an RT on/off.

Gun fires, but air chamber recharge volume & pressure is almost nothing, gun just go's blap.

** If I pull back cocking arm REALLY FIRMLY for a 1/2 second, air chamber pressure and volume come up & gun fires normally.

I have checked sear rod length, made sure trigger has clearance once gun is cocked.

I'M STUMPED

[MournBlade]

My first thought is why? There is no benefit to having an RT on/off on your pump, so why bother changing it out in the first place? Put your original on/off back in.

[Motorhead]

My first thought is why? There is no benefit to having an RT on/off on your pump, so why bother changing it out in the first place? Put your original on/off back in.

Why? .... 1/2 the trigger pull weight

[Old School 626]

What shape is your sear in? And the part of the bolt the sear grabs?

How about your bumper? Change it recently?

here's what I'm thinking: In your quest to lessen your trigger pull you are putting also putting less pressure on the sear to hang on to the bolt and because of that it's coming to rest being not all the way back against the bumper, it's stopping short of it's "home" position so that the sear is not fully engaged and the O/O is not opening up all the way to recharge the dump chamber.

Something else you might try to lighten the trigger pull for pump is: If you want to lower your trigger pull for pump maybe put the stock O/O back in and mod the sear by making the arm longer and attaching the "push rod" portion lower so that you have more leverage? It'll make the pull longer but potentially much lighter.

[Spider-TW]

Gun fires, but air chamber recharge volume & pressure is almost nothing, gun just go's blap.

** If I pull back cocking arm REALLY FIRMLY for a 1/2 second, air chamber pressure and volume come up & gun fires normally.

I think the following is happening;

When you push the bolt all the way back the sear goes up to the bolt as far as possible, letting the valve recharge. When you release the pump, the bolt comes forward against the sear. The cut of the sear on the bolt face makes the sear slide down a little, pushing the on/off pin up and cutting off your recharge.

Try a shorter on/off pin. As an experiment, you can loosen your rear frame screw on the light side of finger tight, to possibly prove the theory.

Also check that there isn't a piece of paintball shell or grit under the sear pin in the frame. Something pushing the sear up a hair would do the same thing.

[Motorhead]

Please keep em coming .....

** Tried this before heading off to work this morning.

The bolt return spring in the gun was the older style black spring * ... Measured a New style gold spring and found coil diameter a tad smaller on the gold spring, installed it and marker is much better, but still not quite right yet. You can now hear chamber recharging with a loud hiss, and after a second or so marker fires normally.

* So my guess is that sear is now going up against bolt a tiny bit more allowing on/off pin to drop a little bit more. So my thoughts are the on/off pin is too long by @ .010" or more ?


Your thoughts

Scott

[Old School 626]

Try this,

Take a grip panel off and see if you can move the sear arm forward at all.

If you can't then you pin just might be too long.

If you can you need to find out why and address it before you go altering the pin.

Kinda like two wrongs don't make a right.

Ya know?

[michbich]

Try to messure the pin with a micrometer or caliper.

[Motorhead]

Try to measure the pin with a micrometer or caliper.

Yup, once I get home will pull the pin and measure it up.
Based upon this THREAD: http://www.automags.org/forums/showthread.php?t=67604
Looks like I need it to be .750" length.

[Motorhead]

Yup, once I get home will pull the pin and measure it up.
Based upon this THREAD: http://www.automags.org/forums/showthread.php?t=67604
Looks like I need it to be .750" length.

Just for prosperity, checked sear forward movement once cocked, Nope sear won't move any further. Measured RT on/off stem, .750" per specs.

* Removed stem from on/off and ground it down .010" to .740" .... wala marker operates perfectly.

IMO just tolerance issues with the parts fit between models and years produced.

** It did what others have said, cut the trigger pull poundage in half