HDD in 1377 and other Q's

HDD in 1377 and other Q's

Joined: March 1st, 2002, 12:22 am

June 16th, 2011, 7:15 pm #1


started searching here and Yellow for DV1377 info et al. Looking ot build a garden defense carbine, and any kitchen table mods I can do to get decent performance I'll do.

Research indicates that adding a HDD to a gun like the 1377 helps keep it quiet. I'm assuming that you can tune the gun to dump all the pumps you put in, or you can tune it to keep a few ... a sort of "low-tech" AC build.

Does the HDD work with the plastic crosman breech (metal breech was specifically mentioned...)?  Does hammer wieght play a part in this? (Scott's assertion that a lot of guns have too much hammer wieght apply here?)  Is a good starting point a decent 1377 build (usual tuning stuff, valve work, hammer adjuster, hammer spring, valve springs etc) then apply the HDD and tweak the hammer settings? I can see I'm gonna need a chrony.....

TIA

 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
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Joined: November 28th, 2002, 6:26 pm

June 16th, 2011, 9:10 pm #2

...operation. It's prettymuch pointless.

And no - my HDD doesn't work with the old Crosman plastic breech.

Steve
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Joined: March 1st, 2002, 12:22 am

June 16th, 2011, 9:33 pm #3


HDD issues aside.....

So I wont need specialized valve?


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
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Joined: November 28th, 2002, 6:26 pm

June 16th, 2011, 9:43 pm #4

...without reducing power - you can get full stock power on 5 instead of 10 pumps without ever taking the valve out of the gun.

http://www.network54.com/Forum/275684/m ... g+adjuster.

Steve
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Joined: March 1st, 2002, 12:22 am

June 16th, 2011, 10:04 pm #5


using the adjuster?

Pump it 10 times, shoot over chrony, record FPS #'s, repeat a few times to get a good average

Then pump 5 times, shoot over chrony, adjust hammer spring, repeat until numbers begin to resemble the average?

And quieter.. always a bonus 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
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Joined: November 28th, 2002, 6:26 pm

June 16th, 2011, 10:39 pm #6

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Joined: March 1st, 2002, 12:22 am

June 16th, 2011, 10:54 pm #7


on the ninth pump, the efort it takes to close the pump arm is (in your example) the same as needed to release the indicator?

Does that mean you need to bottom out every stroke so it can test until its at the correct pressure? 

 


dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
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Joined: November 28th, 2002, 6:26 pm

June 16th, 2011, 11:42 pm #8

...the closed arm against the tube that actuates the sensor. When the force of the sensor spring can no longer resist the force of pressure, the arm snaps and stays against the tube, forcing the sensor button to protrude.

I find that when pumping against signficant pressure, the natural tendency of the arm to snap over-center prettymuch guarantees the arm will always "bottom out." Is your experience different?

Steve
Last edited by pneuguy on June 16th, 2011, 11:42 pm, edited 1 time in total.
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