another pnue-mag question

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  • mikecaz
    Registered User
    • Aug 2006
    • 168
    #1

    another pnue-mag question

    Ok I have it all together and I was doing some testing and it appears that it will work with lower pressures jsut wont fire very well and if I put it to normal operating pressure the piston will not fire the gun. So what I am thinking is that the piston is not far enough down on the the dear arm to fire it at the high pressures. So my question is how far down on the sear arm should the piston be contacting it? The farther down the more mechanical advantage it will have. So what do you all suggest?

    Thanks in Advance
    Tags: None
    • Spider-TW
      U R techno-literate!

      • Oct 2006
      • 3554
      #2
      Do you have an RT on/off in it?

      And what range of pressure are you using on your LPR?

        Comment

        • Smoothice
          Registered User

          • Nov 2006
          • 4579
          #3
          Do you have enough air in your tank? Silly question but it has stumped me for a few minutes before.

          How about your velocity? Turn it up - down - all around. This has also stumped me before.

          Is everything oiled up? Again this has caused my pneumag not to fire normally.

            Comment

            • BigEvil
              www.BigEvilOnline.com

              • Feb 2005
              • 9333
              #4
              Someone can correct me if im wrong, but I have ALWAYS put the piston as low on the sear as I could. Leverage is your friend.

              There should be a gap between the ram and the sear when the gun is gassed up. It seemed to me that this is essential to get the gun to fire. Some people have referred to this as 'pre-travel'. Think of it as giving the ram a little head-start before hitting the sear.

                Comment

                • Spider-TW
                  U R techno-literate!

                  • Oct 2006
                  • 3554
                  #5
                  Originally posted by BigEvil
                  Someone can correct me if im wrong, but I have ALWAYS put the piston as low on the sear as I could. Leverage is your friend.

                  There should be a gap between the ram and the sear when the gun is gassed up. It seemed to me that this is essential to get the gun to fire. Some people have referred to this as 'pre-travel'. Think of it as giving the ram a little head-start before hitting the sear.
                  Lower IS better. Someone here (apologies for the murky memory) angled their MPA-3 down a little to help with that after having mounted the ram already. The only concern was that it would wear more than usual.

                  I think the gap keeps the ram from interfering with the normal operation of the sear. When you are positioning the MPA-3 without air, the bolt isn't pulling the sear tight against the sear pin and the frame. With pressure on the bolt, the whole assembly pulls forward a little. Also, the actual 'ram' piece of the MPA-3 has air distribution grooves to let the air across the face of the ram, but to avoid a sticky ram, a little run at the sear is good to get the seal moving (dynamic friction < static friction, yes-yes). That gap can be filed or ground down on the ram since you usually have the ram mounted by the time you realize there isn't a gap at all. (doh!) Keep the metal bits out of your MPA-3 and everything else!

                    Comment

                    • Mongoose
                      VenomousDesigns.com

                      • Nov 2006
                      • 1593
                      #6
                      Originally posted by BigEvil
                      Someone can correct me if im wrong, but I have ALWAYS put the piston as low on the sear as I could. Leverage is your friend.

                      There should be a gap between the ram and the sear when the gun is gassed up. It seemed to me that this is essential to get the gun to fire. Some people have referred to this as 'pre-travel'. Think of it as giving the ram a little head-start before hitting the sear.
                      what he said /\
                      the lower the better, just make sure your as horizontal as possible...that helps alot

                        Comment

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